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Quality and grading

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

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 refraction quality and a metal-like steely look (compared to milky, dull and flat looking surfaces), the higher the lustre the higher the value.

Colour

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

 

20mm south sea saltwater pearlAn over 20mm South Sea Pearl Beauty - out of the safe!

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.

Surface Flaws

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 Seas 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.

Matching

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.