Rubies
They steal is the noblest monocrystalline variety of aluminum oxide (To the 2O3), a famous mineral like corundum, strongly (you see color of minerals) and only natural substance of hardness 9 in the Scale of Mohs. It is introduced of lively red color, had to chromium inclusions, but it can assume several tonalities of this color, that they go from the alive one, also said “pigeon blood”, to the rosato one. Its dimensions usually are not exceptional and are tied to the transparency; for this they are thought exceptional the runies limpid that exceeds the 10 carats. Always based on the quality, several typologies are used for the cut. The best gems usually are cut “to facets”, while to decreasing of the transparency it passes to the shape of “cabochon”; this modality of cut is, moreover, the best one in order to put in prominence, laddove present, the phenomenon of the asterismo. They steal, is for its much limited production, than for the great beauty, it has been always counterfeit, using other minerals as the spinel (Steals balas), with granato variety like almandino and piropo (They steal of Boemia), with the zircon, the topaz (Steal of Brasi them) and with the tormalina (Steal of Siberia). Lately many analyses have been executed on the antichi jewels and one of the most famous errors was found in i jewels of the British crown, with “Steal of the black prince” and “They steal of the Timur”, both recognized like spinels. Famous they are the present giacimenti in Sri Lanka, Tanzania, China, Vietnam and Thailandia, but those of better quality they come from the Birmania, extracted in the mines of Mogok.