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. Topaz from Utah are small, but display a lovely colour. They also form very pleasing groups, something of a rare occurrence with this mineral.