Just as Diamonds have set criteria for determining quality, pearls have a similar but different set of factors which govern their quality.
This is the name given to the loveliest attribute of a pearl, the shimmering rainbow dancing across the surface. The deeper the nacreous coating a pearl has –the better the lustre seen.
Scientifically speaking it is the quality of light on the surface when light rays are reflected and refracted by a process called interference.
This phenomenon occurs when light meets very thin films or layers of material; in this case the individual layers of nacre, creating an effect similar to a prism by breaking up light waves into their component wavelengths and therefore colours.
It is the most important single factor when judging quality.
Ideally a pearl will have a completely blemish free surface, without bumps or gaps caused by uneven coating by the mollusc. It is a factor, which is ultimately beyond the control of the farmer.
In reality most pearls are not born perfect –again like us, and some markings are to be expected. These add to their individuality and personality.
The more perfect the skin the higher the resulting price.
In market terms when referring to Seawater Cultured Pearls of all types, a perfect round or drop shape is generally considered to be most desirable. Whilst attempting to achieve this, the farmer will also harvest pearls of other shapes; these include off round, oval, baroque, Keshi and stages in-between.
Each of these shapes have there own particular loveliness and purpose, and as ever with these things, the beauty is in the eye of the beholder.
With specific regard to freshwater pearls, part of their intrinsic appeal is their incredible diversity of shape.
With Pearls colour is a complex issue.
White pearls are never actually simply white, there are numerous overtones and subtle shades from pink through to gold- some more attractive than others.
The range of none white colours is vast. Practically all the spectrum colours are represented.
This can further be divided into naturally occurring colours; such as those of Tahitian and South Pearls and the Pink to Peach hues of Freshwater pearls, and those brought about by alterations such as the silver nitrate treatments to Akoya pearls to change them to black or grey. Its possible to dye pearls almost any colour –but general only occurs with low value Pearls purely for fun.
A pearl of natural colour will always be more valuable and therefore expensive, than one of induced colouration. The alteration of colour is perfectly acceptable as long as it is full disclosed.
The deciding factors when considering colour are what suits your individual skin tone and budget best.
The issue of size is relative to the type of Pearl in question and is inextricably linked to the size of the parent Mollusc.
Larger Molluscs produce larger pearls. The largest pearls are produced by the Australian white lipped Oyster (Pinctada Maxima) which is almost the size of a dinner plate. It can produce pearls up to an incredible 22mm diameter. Commercially speaking, a bigger pearl will always be more valuable than a smaller pearl of the same quality.
When assessing Pearl quality, it’s an amalgamation of the above factors which decides a Pearls overall quality status.
Just as with diamonds, there is no one universally recognised grading system, but the most common method involves denoting the letter “A” as “star” rating, in the same manner used by hotels. The more “A’s” given, the higher the quality –the highest being generally between three and five “A’s”.
This assumes of course that everyone uses the same standards of judgement and the playing field is level-this of course, as in many facets of life, is not the case.