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. Beautiful specimen of imperial topaz from Ouro Preto, the only place in the world where this beautiful and appreciated variety of topaz appears.