Updated: May 14, 2020
Al2SiO4(F,OH)2 Hardness of 8 化学成分：Al2SiO4(F,OH)2 宝石硬度：8
Although topazes exist in a wide range of colours, when the word "Topaz" is mentioned, majority of the general public will imagine a blue stone. So what does adding a prefix as regal as "Imperial" mean? 尽管托帕石有多种颜色，但当提及“托帕石”一词时，大多数的人会在脑海里浮现一块蓝色宝石。那么，加了前缀的“帝王”的托帕石代表着什么呢？ There are 2 theories from which Imperial Topaz got its name:
The first spoke of honouring the royal family of the Russian Czars in the 1800s, who claimed the exclusive rights to the pink topaz that were mined at The Ural Mountains. The second was attributed to the Brazilian Empire when Brazilian/Portuguese Emperor Peter II visited the town of Ouro Preto and was presented with a reddish topaz by Professor Henry Gorceix in 1881.
This was how certain colours of topazes came to be associated with royalties. Today, the name "Imperial Topaz" refers to orangy-red, pink and red topaz. Due to the presence of chromium, a reddish pleochroic colour is often present at the ends of fashioned gems like pears and ovals worthy to be titled "Imperial" by dealers.
As topazes are usually clean, 95% of yellow-to-orange topazes being heat-treated to pink or red are difficult to distinguish from the untreated ones. This makes a truly red untreated topaz, even with slight inclusion, exceptionally rare, valuable and highly coveted by gem connoisseurs. Having only less than one-half of 1 percent being of gem-grade material, this makes red topaz the most sought-after of all colours and they are mostly available only in small sizes! Due to its rarity, it is no surprise that there is an exponential jump in the value for stones larger than 5 carats and again for 10 carats and above for this November birthstone. Sources from GIA, IGS, AJU AJS, gem society.
95％的黄色至橙色托帕石是被加热处理过的，为了达到粉红色或红色的帝王色，由于托帕石通常是很干净极少有内含物，因此很难区分开来加热处理过的和天然的。这使得天然红色并未经过加热处理的托帕石异常珍贵，即使稍有内含物，却依然极为稀有，名贵且受到宝石鉴定家的垂涎。 鉴于只有不到1％的一半的材料是宝石级别，这使得红色托帕石成为所有颜色中最抢手的，并且大多数的尺寸都偏小!由于它的稀有性，这枚属于11月份的诞生石，大于5克拉的价格跳跃幅度就非常大，甚至于10克拉及以上的，不难想到其珍稀程度与价值。 资源收集于GIA，IGS，AJU AJS和宝石学会的信息。