Tag Archives: nacre

A Guide to Pearl Qualities and Grades

Buying pearls can be confusing – there are many myths and misconceptions. The days of the pearl fisherman diving off the side of a small boat to harvest pearls from the ocean floor is mostly gone. Wild pearls still exist but are difficult to find and are often protected from harvesting. Nowadays, most pearls are cultivated in freshwater lakes and rivers or seawater rafts.

Pearl Grades; There is no international standard for grading pearls so identical pearls may be graded differently by different suppliers. However, grading takes into account shape, lustre, surface quality, nacre thickness and matching on the strand. Grading a strand of pearls like a necklace is slightly different to grading individual pearls as not every pearl on the strand will necessarily meet all the criteria.

  • GRADE A, Shape near round, Lustre fair, Surface <75% clean, Nacre 0.25 to 0.35mm, Matching fair.
  • Grade AA,  Shape mostly round, Lustre good, Surface >75% clean,  Nacre 0.35 to 0.5mm, Matching very good.
  • Grade AAA, Shape round, Lustre high, Surface >90% clean, Nacre over 0.5mm, Matching very good.

Shape; Pearls develop into a variety of shapes. Round pearls are the rarest and the highest priced. The term ’round’ does not mean spherical like a marble but the pearls should not look obviously oval or flattened to the naked eye.  Non-round pearls can offer value for money. Wild pearls are rarely round so different shapes could be thought more natural.  There are a variety of shapes including round, near round, circle, oval, drop, baroque.

Lustre; This is the shine that gives pearls their beauty and is an important buying factor. Lustre refers to the pearls brilliance – the way it’s surface reflects light, and to the inner glow – how it refracts light from the layers of nacre within.

Surface Quality; Pearls are a natural product and small natural imperfections are quite acceptable – even desirable. Unacceptable faults include cracks or holes in the surface and thin or flaking nacre.

Matching; This compares all the pearls on the strand with each other to see how they match. They don’t have to be identical – that can seem artificial and real pearls will vary a little.