Topaz
黄玉
Topaz is a hard, transparent mineral. It is a compound of aluminum, silica, and fluorine.
黄玉是一种坚硬、透明的矿物质。它是铝、硅和氟的化合物。
Gem topaz is valuable. Jewelers call this variety of the stone “precious topaz”. The best-known precious topaz gems range in color from rich yellow to light brown or pinkish red. Topaz is one of the hardest gem minerals. In the mineral table of hardness, it has a rating of 8, which means that a knife cannot cut it, and that topaz will scratch quartz.
宝石级黄玉价值不菲。珠宝商把这种石头称为“贵黄玉”。最出名的贵黄玉有各种颜色，如深黄色、淡棕色、浅红色等。黄玉是最坚硬的宝石矿中的一种。在矿石硬度表上，它的硬度为8，这表明刀子不能割开它而它可在石英上划痕。
The golden variety of precious topaz is quite uncommon. Most of the world’s topaz is white or blue. The white and blue crystals of topaz are large, often weighing thousands of carats. For this reason, the value of topaz does not depend so much on its size as it does with diamonds and many other precious stones, where the value increases about four times with each doubling of weight. The value of a topaz is largely determined by its quality. But color is also important: blue topaz, for instance, is often irradiated to deepen and improve its color.
金色的贵黄玉品种非常罕见。世界上大多数的黄玉是白色或蓝色的。这些白色或蓝色的黄玉晶体很大，常常有数千克拉重。由于这个原因，黄玉的价值不像钻石和许多其它宝石那样主要依赖于其大小，重量翻一番价值即上升约四倍。黄玉的价值很大程度上取决于其品质，但颜色也很重要。举例来说，蓝色的黄玉常需放射处理以加深和改善其颜色。
Blue topaz is often sold as aquamarine and a variety of brown quartz is widely sold as topaz. The quartz is much less brilliant and more plentiful than true topaz. Most of it is variety of amethyst: that heat has turned brown.
蓝色的黄玉常被作为海蓝宝出售，许多种棕色石英则被当作黄玉广为贩卖。石英光亮度远小于黄玉，矿藏储量也远较黄玉丰富。大多数石英是一种紫水晶，高温使其变为棕色。
注：黄玉，矿物学家也称之为黄晶，英文名Topaz，国内珠宝界常称之为托帕石，为英文的音译。这主要是因为无论是黄玉还是黄晶，都会和我国珠宝界原有的一些宝石的称呼相混淆。在我国，黄色的和田玉（软玉）长期被称为黄玉，尤其是在考古界；而黄晶又和水晶中的黄水晶容易相混。（来源：百度百科）
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