Topaz was chosen by the geologist Friedrich Mohs to represent grade 8 in his famous scale first published in 1825 and which is still valid today. Without doubt it is one of the great gems and a mineral that stands out in any collection due to the beauty, colour and size, sometimes of gigantic proportions, of its crystals. This specimen comes from the mine "Capao" near Ouro Preto, the only region in the world where this valuable variety of topaz appears. In one of the images one can see five of the six facets of the quartz crystal prism, wherein the topaz was formed.