.

Sunday, March 15, 2015

TAAF 2015 Stamp Issue
Beryl









:: TAAF (Terres Australes et Antarctiques Françaises)
 :: THEME: Beryl
  :: NOMINAL VALUE: 0.66€ 
   :: ISSUE DATE: 1 January 2015
    :: STAMP DESIGN: Claude Perchat
     
    

Aquamarine and maxixe

Aquamarine (from Latin: aqua marina, "water of the sea") is a blue or cyan variety of beryl. It occurs at most localities which yield ordinary beryl. The gem-gravel placer deposits of Sri Lanka contain aquamarine. Clear yellow beryl, such as that occurring in Brazil, is sometimes called aquamarine chrysolite. The deep blue version of aquamarine is called maxixe. Maxixe is commonly found in the country of Madagascar. Its color fades to white when exposed to sunlight or is subjected to heat treatment, though the color returns with irradiation.


Emerald

Emerald is a rare and valuable gemstone and, as such, it has provided the incentive for developing synthetic emeralds. Both hydrothermal and flux-growth synthetics have been produced. The first commercially successful emerald synthesis process was that of Carroll Chatham. The other large producer of flux emeralds was Pierre Gilson Sr., which has been on the market since 1964. Gilson's emeralds are usually grown on natural colorless beryl seeds which become coated on both sides. Growth occurs at the rate of 1 mm per month, a typical seven-month growth run producing emerald crystals of 7 mm of thickness.



Golden beryl and heliodor
Golden beryl can range in colors from pale yellow to a brilliant gold. Unlike emerald, golden beryl has very few flaws. The term "golden beryl" is sometimes synonymous with heliodor (from Greek hēlios – "sun" + dōron – "gift") but golden beryl refers to pure yellow or golden yellow shades, while heliodor refers to the greenish-yellow shades. Both golden beryl and heliodor are used as gems. Probably the largest cut golden beryl is the flawless 2054 carat stone on display in the Hall of Gems, Washington, D.C., United States


Goshenite
Colorless beryl is called goshenite, gem value of goshenite is relatively low. The name originates from Goshen, Massachusetts where it was originally discovered. Since all these color varieties are caused by impurities and pure beryl is colorless, it might be tempting to assume that goshenite is the purest variety of beryl. However, there are several elements that can act as inhibitors to color in beryl and so this assumption may not always be true. In the past, goshenite was used for manufacturing eyeglasses and lenses owing to its transparency. 

Morganite
Morganite, also known as "pink beryl", "rose beryl", "pink emerald", and "cesian (or caesian) beryl", is a rare light pink to rose-colored gem-quality variety of beryl. On October 7, 1989, one of the largest gem morganite specimens ever uncovered, eventually called "The Rose of Maine" was found at the Bennett Quarry in Buckfield, Maine, US. The crystal, originally somewhat orange in hue, was 23 cm (9 in) long and about 30 cm (12 in) across, and weighed (along with its matrix) just over 23 kg50 pounds.

Red beryl
Red beryl (also known as "red emerald" or "scarlet emerald") is a red variety of beryl. The old synonym "bixbite" is deprecated from the CIBJO, because of the risk of confusion with the mineral bixbyite (also named after the mineralogist Maynard Bixby). Red beryl is very rare. The greatest concentration of gem-grade red beryl comes from the Ruby-Violet Claim in the Wah Wah Mountains of the Thomas range of mid-western Utah. Prices for top quality natural red beryl can be as high as $10,000 per carat for finished stones.