Garnet not like sapphire blue in subdued daylight but more reminiscent of the grayish blues and greenish blues sometimes seen in spinel. However, in white LED light, the color is equal to the best cornflower blue sapphire, or D block tanzanite; this is due to the blue garnet's ability to absorb the yellow component of the emitted light. Pyrope is an indicator mineral for high-pressure rocks. The garnets from mantle-derived rocks, peridotites, and eclogites commonly contain a pyrope variety. Spessartine or spessartite is manganese aluminium garnet, MnAl(SiO). Its name is derived from Spessart in Bavaria. It occurs most often in granite
Diamond (gemstone) the Roman writer Pliny the Elder noted diamond's ornamental uses, as well as its usefulness to engravers because of its hardness. It is however highly doubtful that Pliny actually meant diamonds and it is assumed that in fact several different minerals such as corundum, spinel, or even a mixture with magnetite were all referred to by the word "adamas". Diamonds eventually spread throughout the world, even though India had remained the only major source of the gemstone until the discovery of diamonds in Brazil in 1725. A Chinese work from the 3rd century BC mentions: "Foreigners wear it [diamond] in