Tag Archives: Topaz

RMC Gems “One Stop Source for all Gemstones”


RMC gems Thai is amongst the biggest and has a reputation of being a reliable gemstone supplier with sales offices in Bangkok, Hong Kong and Japan. For jewelry manufacturers it is very important to have a constant supply with perfectly maintained quality where the producers of fine jewelry can source all their gemstones in one place. Therefore RMC is a one-stop shop, with its product line comprising gemstones of all types –suitable for makers of silver, gold or platinum jewelry. There is a full range of topaz, tourmalines, tanzanite, morganite, opals, spinels, kunzite, natural zircon, rubies, emeralds, sapphires, amethysts, garnets, citrines and even more varieties of gemstones.


RMC believes in the principle that “any task undertaken should to be done differently, or else don’t embark on a job at all”. By following this ideology, the company does a great business and has built excellent relationships with its customers over the years.

RMC specializes in tourmaline, topaz, tanzanite and other precious beads in every conceivable color, shape and size with a complete range. In Tourmaline, from Paraiba, rubelite, pink and green tourmalines and in topaz from white to sky blue, Swiss blue, London blue and mystic topaz. In tanzanite, RMC stocks small calibrated stones, right up to single stones even up to 500 carats, and such a big size is incredibly rare in the market.

The Company has its own manufacturing facilities in Thailand, India and China providing an edge of having the best skills from all over the world. The sourcing of raw material is done in-house, which makes the cost of the product reasonable.

Headquarters RMC Gems Thai Co., LTD., 8 Soi Pramote 3 Mahaesak Road, Bangrak, Bangkok 10500, Thailand
Phone :
(66-2) 635 9101 Fax : (66-2) 635 8707


When heated, yellow topaz often becomes reddish-pink. The color change upon heating was first discovered by a Parisian jeweler around 1750. In particular the yellow Topaz of Brazil has been known to be treated frequently, by wrapping Topaz in Asbestos. Only stones of a brown-yellow color yield the pink; the pale yellow ones usually turn white. The pink color is stable. [1]. Topaz can also be irradiated, turning the stone blue, ranging from a light pure color to very dark almost electric blue. A recent trend in jewelry is the manufacture of topaz specimens that display iridescent colors, by applying a thin layer of titanium oxide via physical vapor deposition, this stone is then sold as ‘mystic topaz’.


An Overview of Topaz

Topaz is a silicate mineral of aluminium and fluorine with the chemical formula Al2SiO4(F,OH)2. It crystallizes in the orthorhombic group and its crystals are mostly prismatic terminated by pyramidal and other faces, the basal pinacoid often being present. It has an easy and perfect basal cleavage, meaning that gemstones or other fine specimens have to be handled with care to avoid developing cleavage flaws. The fracture is conchoidal to uneven. Topaz has a hardness of 8, a specific gravity of 3.4–3.6, and a vitreous luster. Pure topaz is transparent but is usually tinted by impurities; typical topaz is wine or straw-yellow. They may also be white, gray, green, blue, pink or reddish-yellow and transparent or translucent.