About Pearl Magpie Jewellery
- Types of Pearl
- Akoya Pearl Oyster
- Keshi Cultured Pearls
- Valuing Pearls
- About Surface Blemishes
- Comon Necklace Names and Lengths
- Caring for your Pearls
- Pearl Tips & Tricks
Pearls are a mollusc’s response to an irritating object inside their shells. These irritants either occur naturally, such as in the case of a parasite or predator's bite (resulting in a Natural pearl) or are surgically placed there by human intervention, "bead nucleation" and "mantle nucleation", result in a Cultured pearl. The entombing process that forms the pearl happens by the mollusc secreting saliva (Nacre) to form this wonderful gift of God that is a Pearl.
Before the beginning of the 20th Century, pearl diving was the most common way of harvesting pearls. Now, however, almost all pearls used for jewellery are cultured by planting a seed or nucleus into pearl oysters, bead nucleation, to produce saltwater pearls or mussels to produce freshwater pearls. The nucleus is surgically implanted in the oyster's gonads and is generally a polished bead made from special mussel shell along with a small graft of mantle tissue from a live oyster. Freshwater Pearls are typically mantle-nucleated, meaning they are composed entirely of nacre; the fragment of mantle tissue disintegrates as the mollusc coats it, resulting in a pearl made of solid nacre. Although methods are changing and freshwater pearls are also being nucleated with pearl beads as in the production of saltwater pearls, this is truer as the size of the pearl increases. As Saltwater Pearls are nucleated with a seed and mantle tissue the resulting pearl is normally larger and rounder in shape than freshwater pearls. Technical evolution now enables freshwater mussels to be seed-nucleated thus producing freshwater pearls akin to saltwater pearls. Cultivation takes from two to four years depending on conditions, variety and whether it is a fresh or salt water medium. A typical fresh water mussel can produce up to 50 pearls at a time whereas their saltwater cousin can only produce 1 or 2 pearls at a time and taking much longer to do so.
Calcium Carbonate (CaCO3) & Conchiolin
Nacre is the material of Pearls, and is also known as "mother of pearl" or "sadaf" it is the deposit of layers of crystalline calcium carbonate held together by an organic horn-like compound called conchiolin. This combination of calcium carbonate and conchiolin is what gives pearls their uniqueness, value and beauty.
Nacre is secreted by the ectodermic cells of the mantle tissue of certain species of mollusc. In these molluscs, nacre is continually deposited onto the inner surface of the animal's shell (the iridescent nacreous layer, commonly known as mother of pearl), both as a means to smooth the shell itself and as a defense against parasitic organisms and damaging detritus. When a mollusc is invaded by a parasite or is irritated by a foreign object that the animal cannot eject, a process known as encystation, entombs the offending entity in successive, concentric layers of nacre. This process eventually forms what we call pearls and continues for as long as the mollusc lives.
Types of Pearl
Freshwater pearls come from Molluscs that for simplicity sake we call 'Mussels' whereas Saltwater pearls are produced from Oysters. there are two families of mussels that produce freshwater pearls regularly, they are Margaritiferidae and Unionidae. Margaritiferidae is widely distributed in the Northern latitudes and would include areas such as Northern Europe, Japan and Northern America. However most of our freshwater pearls come from the Unioidae family, particularly the Genus Hyriopsis.
Freshwater pearls are particularly known for their wide range of whimsical shapes and colours, they are plentiful and an affordable alternative to their more expensive saltwater cousins. However, the closer to round and large, the higher the price comparing well with Akoya pearls. Freshwater pearls can come from anywhere there is a supply of fresh water, but in practice the major fresh water farms are in China on the Yangtze River Delta. In China the most prevalent mussel that produces cultivated pearls is Hyriopsis cumingii that produces a variety of coloured pearls, and Cristaria plicata that produces mainly white, cream and some pink pearls. In Japan on Lake Biwa and to a lesser degree, Lake Kasumigaura, have developed many varieties with doubtful sucess rates and the main production comes from the Hyriopsis schlegelii. Freshwater pearls are found in many other parts of the world, particularly from the United States of America around the Mississippi River Basin.
Akoya Pearl Oyster
Japanese Akoya Pearl - (Pinctada fucata (martensii)
Akoya is a historical name given to the Japanese Pearl Oyster. Today it is the term used to describe the actual pearl produced by the Akoya Pearl Oyster. In simple terms an Akoya Pearl is a pearl cultured in a Saltwater Pinctada fucata Oyster and using a bead nucleus as distinct from a Freshwater pearl, Keshi pearl and a South Sea pearl. The Akoya Pearl Oyster is a hardy animal and thrives in Northern Japanese and Korean waters where the temperatures fluctuate and are colder than their warmer watered Pacific cousins. The Japanese Seas have become increasingly more polluted as the Population and Industry increases; this has decreased the local production of the much prised Japanese Akoya pearl known for their high quality and brilliant white colour, immortalized by “Mikimoto”. The Japanese Akoya pearls range in size from 2mm up to approx 11mm and do not grow much above this due to factors such as the small size of the mollusc, the slow growth rate of the pearls in cold temperatures and the commercial pressures on the farmers to harvest the pearls. It is reported that a large proportion of Japanese Akoya pearls sold today are imported from China and processed in Japan, where the techniques and experience in Culturing pearls are long established. .
Chinese Akoya Pearl Oyster - Pinctada chemnitzii
The Chinese have had more success with the culturing of the Pinctada Chemnitzii (although both P. fucata and P. chemnitzii are used) P. chemnitzii favours waters from the Kyushu Islands south to the China Sea and produces what is popularly called a Chinese Akoya Cultured Pearl or just Chinese Akoya. The Akoya produced is generally a smaller pearl of approximately 7-8mm in diameter and are brilliantly white in the main but may come in a rainbow of other colours. The traditional qualities of Akoya Pearls are their small size, round shape, extremely high lustre, clean surfaces and brilliant colour palette As the Akoya is bead nucleated it often has a “tail” of nacre, varying in shape and size, these are called “Baroque Akoya Pearls” we often use them for unusual designs in jewellery as they have interesting and distinctive asymmetrical shapes
South Seas Pearls - Silver-Lip oyster & Gold-Lip oyster - Pinctada maxima
The majority of South Sea Pearls come from the large but difficult to cultivate Pinctada Maxima which suffers high mortality rates, The successful ones can produce beautiful pearls of between 8mm and 20mm, with 13mm being the average. Only 10 to30% of the harvest will produce round (or near round) pearls, the rest being baroque and drop shaped, are still highly valued because of their beauty and relative rarity. The White South Seas Pearls come mainly from Australia. Other centres are Indonesia and the Phillipines.
Tahitian Pearls - Black-Lip oyster - Pinctada margaritifera
Tahitian Pearls are so named because they are found mainly in the French Polynesian Islands. The Tahitian black lipped oyster produces a stunning array of iridescent black, grey, and greenish black saltwater pearls. The cultivation and export of true Tahitian pearls are government controlled to ensure consistent quality and minimum standards. Only about 5-10% of pearls produced are round and therefore command high prices but all the other shapes are available and much sought after. The thick nacre of at least 0.8mm ensures high lustre and vivid colours. AAA grade Tahitian pearls are very high lustre and have a clean surface (one to a few slight flaws are distributed over less than 10% of the pearl surface).
Keshi Cultured Pearls & Seed Pearls
The term "Keshi", "Seed" or perhaps "Bead" Pearl, is sometimes used to mistakenly describe a Natural pearl (one that is formed in the wild by nature with no interference from man). “Keshi” is the Japanese word given to very small things and the word has become, through popular usage, used to refer to small pearls produced without nucleation. Therefore, the term for a pearl without a nucleus but produced by a “farmed” or “worked” pearl mollusc, is a “Keshi Cultured Pearl” or “Cultured Keshi Pearl”.
The formation of a Keshi Cultured Pearl (seed pearl) is the result of one of the following:
Firstly, the mollusc rejects the nucleus placed there in the grafting process thus the mantle tissue (epithelium) remains and the nacre forms around this tissue to produce a “Keshi” pearl, just as would happen in the wild with a natural pearl.
The second cause; may be that the mollusc’s mantle was damaged during the implanting operation through inexperienced handling causing epithelium cells to be lodged in mantle tissue and this may create a pearl sack that in turn may produce a Keshi pearl.
(If this injury was to happen in the wild from say a fish bite, then the pearl produced would be a Natural pearl, due to the absence of man’s intervention.)
The third possibility; is that epithelium cells of the mantle tissue are grafted into the body of the mollusc on purpose, to create a Keshi pearl, that is without the inclusion of a bead nucleus.
There is another type of so called “Keshi” that is appearing and that is a Keshi pearl and a nucleus that have been implanted into a pearl sack to fuse together and form a new baroque shape. These are not true Keshi pearls.
There are both Saltwater and Freshwater Cultured Keshi Pearls. As the mollusc does not know the difference between a nucleated implant and a non nucleated implant the resulting pearls will share the same characteristics in colours and properties, although it is rare to find a round Keshi due to the randomness of its original form. Also, the size of Keshi are a lot smaller as a rule due to the absence of a bead nucleus.
The value of the pearls in jewellery is determined firstly by whether the pearls are natural pearls (very rare these days), cultivated saltwater pearls, or cultivated freshwater pearls, and are valued in that order. Then the pearls are valued by a combination of the lustre, color, size, lack of surface flaws, matching and symmetry, All factors being equal, however, the larger the pearl the more valuable it is. Large perfectly round pearls are rare and highly valued.
Lustre is the best expression of a pearl's beauty. It is the quality of the light refracting through the pearl's surface and depends upon the thickness of the translucent layers of nacre. The iridescence that genuine pearls display is caused by the overlapping of successive layers of nacre, these layers break up light passing through the surface producing that special effect of a deep glow, or rainbow effect on a mirror-like surface finish Thick nacre results in high lustre pearls with sharp and intense light refracting quality and a metal-like steely look (compared to milky, dull and flat looking surfaces), the higher the lustre the higher the value.
Pearls usually have a body colour of white but come in numerous other natural colours such as cream, black, gold, etc. The body colour of a pearl is most often naturally enhanced with other overtones. The better the quality such as Tahitian Pearls and South Seas Pearls (saltwater), the overtones are more vivid and exciting. Overtones such as blue, green, gold, silver, pink and reddish purple give rise to expressions of colour such as:
- "Peacock Black" (greenish black)
- "Pistachio Grey" (greenish grey)
- "Cherry" (purplish black)
- "Champagne" (Yellowish grey)
- "Lavender" (bluish black)
- "Tahitian Gold" (golden black)
- "Pigeon grey" (purplish grey)
- "Silver" (grey)
- "Moon Grey" (pale grey)
Size is important with pearls and generally the larger the pearl the more value it will hold. However, all the other factors must be taken into consideration as well, such as Lustre, Shape, Surface Flaws, Colour etc.
Freshwater Pearls, the most plentiful, come in all shapes and sizes from about 3mm up to 12mm and even larger have been recorded but they are rare. Saltwater Pearls start off a little larger than their freshwater cousin mainly because they are seed-nucleated, but still will not usually be allowed to grow to above 20mm.
The average size for pearls sold these days is between 7mm and 8mm.
Also referred to as Cleanliness, and refers to the surface condition of the pearl. naturally occurring disfiguring marks include bumps, depressions, cracks, ridges and other blemishes. All pearls will have some natural flaws, it is to what degree, that will determine the effect on the value. The positive side to slight blemishes is that it proves that the pearl is a genuine natural pearl.
A rough guide may be the grading criteria used for Tahitian Pearls:
|AAA Quality||is for a very high lustre, and a clean surface with a few slight flaws distributed over less than 10% of the pearls surface.|
|AA Quality||is for a medium to high lustre, and a clean surface with a few slight flaws distributed over less than 30% of the pearls surface.|
|A Quality||is for a medium lustre, and a medium surface with slight flaws distributed over less than 60% of the pearls surface.|
|B Quality||are for pearls with heavy spotting or many slight flaws distributed of 60% of the pearls surface.|
It should be noted that South Sea Pearls are graded 'A' through 'D' with 'A' being the finest.
When we at Pearlmagpie.co.uk grade or value pearls, we also take into consideration the Lustre, Surface Flaws, Shape, matching and size. The combinations are too complicated to be meaningful and largely subjective. Thus, we rely on the experience of our graders and our own buyers. If we do give an 'A' rating it will be for all round excellence, weighing all of the pearls qualities.
The beauty of owning a pearl is that it is completely unique, there is not another like it in the world. This is because it is a natural product and man cannot determine how it will grow (unlike a diamond that can be cut to match another). Therefore, 'matching' your string of pearls means to get as close as one can with a natural product. close in size or colour or shape or any combination. it also means that you can 'match' by having say, a large pearl in the centre tapering down to smaller ones on the ends by the clasp. Combinations of 'matching' are limitless. Perhaps 'Mix' also means to 'Match' in pearl jewellery terms.
Symmetry - (Shape)
Pearls come in seven principal shapes, divided into three descriptive categories;
SYPHERICAL - Round and Near Round
SYMMETRICAL – Oval, Button and Drop
BAROQUE – Semi Baroque and True Baroque
There are other factors that may be relevant to describing a shape, for example ridges, rings or circles that go all the way around, then you would describe the pearl as ”Circled Drop Shape” or as otherwise appropriate.
Finally, the pearls may be grown to a certain shape as in the case of coins, crosses, sticks or flats, then you would call it “Coin Shaped” or as otherwise appropriate .
About Surface Blemishes
Blemishes in a pearls surface are formed by obstructions to growth; much like a tree root would experience growing against a wall or a large rock, it grows around. A pearl grows in a pearl sack (nature’s womb) and as the pearl grows in diameter, through the addition of more “rings” of nacre deposit, it will expand outwards. If there is an obstruction such as a dead parasite or harder body parts like a ligament, or tendon then the pearl will deform around the obstacle causing a blemish to the surface, these may take the form of a pit, a ridge or a ring etc. This obstruction may also cause the pearl to grow in directions of least resistance and the pearl may develop as “off round” shape to “baroque” shape. The basic shape is primarily determined by the shape of the original implant in the case of “bead nucleated” pearls or the shape of the implanted mantle tissue in the case of “mantle tissue nucleated” pearls. It is also true that gravity plays a part in the shape of a pearl. In the wild, oysters move around randomly, In the case of Farm Cultured pearls, they are restrained by net “envelopes” that are rotated and cleaned regularly to create the best environment not only for growth but for roundness of shape. Therefore, the presence of blemishes on a pearls surface should not be a detraction, (unless the surface looks like the “moon’s surface”) moderate, light and minor blemishes are acceptable. Only a very small percentage of a pearl harvest produces perfectly round pearls and therefore the closer to true round and the absence of any blemishes, will add to the price demanded.
|Collar : A Collar will sit directly against the throat and not hang down the neck at all, they are often made up of multiple strands of pearls and are 12-13 inches long.||Chokers : Pearl chokers nestle just at the base of the neck and are 13-16 inches long.|
|Princess : The size called A Princess is the "classic" pearl necklace size and comes down to or just below the collarbone and are 16-20 inches long.||Matinee : A Matinee of Pearls falls just above the breasts at 20-26 inches long.|
|Opera : An Opera will be long enough to reach the breastbone or sternum of the wearer and is most suited to evening ware, they are 26-36 inches long.||Rope : A Pearl Rope is any length that falls down further than an opera, over 36 inches long.|
Necklaces can also be classified as uniform, where all the pearls are the same size, graduated, where pearls change in size from large in the center to several millimeters smaller at the ends, and tin cup, where pearls are generally the same size, but separated by lengths of chain.
Pearls are too soft to cut or be polished like other gems, so matching can never be perfect. The pearl's surface, whist tough, is also porous and therefore subject to injury by acids and heat. Therefore, perfume should always be applied before wearing of your pearls. As organic products, they are also subject to decay, it is therefore important to buy the pearls with the thickest nacre.
Caring for your Pearls
The number one care tip we can give is that you must always remember that your pearls are organic and soft in gem terms. the surface of Nacre can be worn-down with constant rubbing or by chemical reaction to perfumes and creams.
Put your perfume on first before your pearls, hand cream before your rings etc.
After use wipe with a soft damp cloth.
Store your pearls in the boxes or pouches provided when you bought them, don't let them rub up against harder jewels in a drawer or box.
Periodically inspect and replace if necessary the 'string'. All strands should be double knotted in case of accidental breakage, (you will not loose all of your pearls in the string).
Pearl Tips & Tricks
There are acceptable pearl enhancements as well as unacceptable enhancements. Here are a few
"Tooth Test" When rubbed across the teeth, real pearls feel gritty while imitation pearls feel smooth.
"Temperature Test" Genuine pearls when touched on the skin will feel cool
"Appearance" It is a little hard to tell the difference between genuine Cultured Pearls and 'Good' fakes simply with the eyes. However, true cultured pearls have a depth to the surface giving a layered effect that reflects the light in a rainbow like look. Fakes are aften "too good to be true" with mirror like surfaces and not a blemish anywhere to be seen, of course this could be a genuine pearl in which case the price will soon tell you, if you are dealing with a reputable source. In many respects it is better to see those natural imperfection like dents, ridges, miss shape and imprints, this points to the origin of the pearl as from Mother Nature not Mans hands.
Setting three-quarter or half pearls into jewelry pieces and selling them as whole pearls. Fully round pearls are far more valuable than those that are semispherical.
Adding a lacquer coating to a pearl to increase it's luster. If you are suspicious about a shiny topcoat, try the "tooth test".
Using epoxy to fill pits and then coating the filling with pearlesence. (compare to body filler in a car repair)
Selling imitation pearls as real pearls. The simple tooth test should spot the difference. Pearls sold as "Majorica pearls", "Atlas Pearls," or "Kultured Pearls" are all imitation pearls.
Selling cultured pearls as natural pearls. Assume that all pearls are cultured pearls due to the scarcity of the natural pearl. Price, Provenance and an x-ray test result should backup a natural claim