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Paraiba Tourmaline

In 1989, Brazilian miners discovered a unique and brightly colored variety of tourmaline in the state of Paraiba. The new type of tourmaline, which soon became known as Paraiba tourmaline, came in unusually vivid blues and greens.  The gemstone world was captivated from the very beginning by the beauty and spirited colors of the Paraiba tourmalines.

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Green Quartz

The 4 types of green quartz:

  1. Natural green quartz from the Montezuma mine
  2. Heat-treated amethyst
  3. Gamma irradiated quartz
  4. Synthetic green quartz

Dr. Henn discussed heating iron-bearing amethyst quartz 400 - 500 C to produce green, followed by gamma irradiation, then heat again to produce a blue violet shade, which he also referred to as blueberry quartz. The colour is attributed to NBO centers (dangling bonds).

Though in his example the starting material was treated amethyst resulting from gamma irradiated colourless or pale yellow material, the starting material could also make use of natural green quartz from the Montezuma mine in Brazil.

Garnet Group

The Mineral and Gemstone Kingdom        
Color Red, reddish-brown, brown, green, yellow, orange, pink, purplish-red, white, colorless, black (Garnet occurs in every color except for blue)
Hardness 6½ - 8½
SG 3.5 - 4.3
RI 1.780 - 1.889
DR None
Luster Pyrope, Almandine, Spessartine, and Grossular have a vitreous luster
Andradite (including Demantoid) and Uvarovite have an adamantine luster

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Demantoid Garnet

Demantoids can be heat treated

Laboratory Approaches Towards Disclosure

In the beginning the labs would not make the heat-or-no-heat call because it was undetectable. As their databases grew and internal characteristics began revealing more clues, new assumptions were made. Below are some of the current approaches the major laboratories are taking.

Read more: Demantoid Garnet

Demantoid Garnet

The demantoid is one of the most brilliant gemstones that exist, yet until recently it was little known except among collectors and gemstone lovers. Strictly speaking it is a green garnet, or rather the star of the green garnets. Not without reason does it bear a name which means 'diamond-like'. The name comes from the Dutch and makes reference to the outstanding quality of this gem, its incomparable brilliance and fire.

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The Geohavens name is an assurance of timeless beauty, distinct quality and uncompromising value. The Company spares no effort in sourcing from the farthest markets and the deepest mines in order to unearth the most attractive gems.

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