Another portion of the base must be sawn away because it contains a cleavage crack that might become larger during cutting. Photo courtesy Sonja Kreis Unique Jewelry.
Alexander Kreis contemplates the original 615 ct Imperial topaz crystal. Photo courtesy Sonja Kreis Unique Jewelry.
A rotating cylindrical screen, known as a trommel, separates heavier minerals—including topaz—from waste rock at the Ouro Preto mines. Photo courtesy Sonja Kreis Unique Jewelry.
The topaz mines around Ouro Preto produce a variety of colors, including purple, pink, golden, natural blue, and the sought-after reddish orange to orange-red Imperial hues. Photo courtesy Sonja Kreis Unique Jewelry.
Today, as in the past, hydraulic mining methods are used to wash the topaz-bearing ore. Photo courtesy Sonja Kreis Unique Jewelry.
如今，欧鲁普雷图是一座繁华的城市，也是联合国教科文组织世界遗产。这里的繁荣、制度和美丽的巴洛克式建筑，一切都是因为这里的矿产资源——即金子、碧玺和拓帕石，这些矿产遍及周围的山上。 图片来源：Sonja Kreis Unique Jewelry 友情提供。
欧鲁普雷图的拓帕石矿目前的产量不如20世纪90年代产量丰富。 图片来源：Sonja Kreis Unique Jewelry 友情提供。
.png "彩色钻石")
.jpg "了解校园课程和在线教育")
