Quality, Rarity and Value, Pricing the Crème de la crème of Gems Part II
By Richard W. Wise
Some gem varieties also sport particular qualities, what I shall call wildcard properties that affect one or more of The Four Cs of Connoisseurship (color, cut clarity, crystal) and will dramatically effect the price of a gem particularly in the upper reaches of quality. The following is a list of wildcard properties, their affects and effects:
Colorless Diamond; (Crystal): Diamonds reputedly from the old
Emerald; (Crystal): They are called old mine stones; emeralds mined in the Sixteenth and Seventeenth Centuries at Colombia’s emerald mines as well as particularly fine gems from Pakistan and Afghanistan that leaked into the Indian market during that period.
Oddly enough green sapphire (Oriental Emerald) was so deeply entrenched in the European psyche that the lovely verdant true emeralds of
There is controversy about what constitutes an old mine stone; some experts maintain it is a pure green hue without secondary hues but it is in fact a honey like quality of transparency also called gota de aceite or “drop of oil”.
I had the privilege of comparing several of these old mine gems. This quality can be s
een when comparing a very fine crystalline emerald mined recently with one of these old mine gems. They do indeed exhibit a thick crystalline quality reminiscent of light passing through honey or oil.
Ruby: Mogok Origin: (Color):
“At a carat there is a price. At a carat and one half that price doubles. At two carats the price triples…at six carats there is no price.”
Jean-Baptiste Tavernier, 1688
In 2005 a world record price for ruby was set when a private client from
56 per carat for an 8.01 carat oval ge
m. This bested the previous record of $228,252/ct. set back in 1988 with a 15.97-ct. gemstone. In
What makes Burma ruby so special is a normally invisible quality of ultraviolet fluorescence, rubies from locations in Thailand, which was the ruby standard bearer in the years between the closing of
Burma in 1962 and the discovery of the new Burma ruby deposits at Mong Hsu in the early 90s, have concentrations of iron that quench the gem’s natural fluorescence. In
r locations in
Some dealers are beginning to discriminate between g
ems produced in the
Blue Sapphire; (Crystal):
amed for their fine color and the quality of transparency or crystal, that is variously described as a velvety, milky, misty, fuzzy glow. This affect is the result of light passing through myriads of extremely small inclusions called, variously flour, sugar or snow. Like the Starship Enterprise passing through an asteroid belt, light colliding with these tiny particles results in the signature fuzziness in the
The image (left) shows a Kashmir sapphire of indifferent color with a very distinctive velvety glow: The affect is often difficult to capture in an image. The image (below left) shows a Kasmir sapphire in its full glory, fine color and glow. (image courtesy Pala International)
Padparadscha Sapphire; (Color; saturation/Crystal): Speaking of padparadscha (see Grading the creme, Part I); though some experts insist upon Sri Lankan (
stones with less than 20% pink and pink stones without similar percentage of orange secondary hue should not be considered. The gem pictured ( right) is a padparadscha sapphire from Malawi, West Africa.
Some padparadscha’s will exhibit a strong orangy fluorescence under ultraviolet. Like the rubies of
saturation of color in the gem. To much fluorescence may overcharge, that is, reduce the transparency or crystal of the gem. Moderate orange fluorescence can be a plus though one not truly recognized or quantified by the market.
The best of these copper colored beauties are a medium toned Caribbean Blue, a visually pure highly saturated blue similar to the color of the shallow waters of the
Cupriian tourmaline from
To be continued...
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