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The term porphyry is from the Ancient Greek πορφύρα (porphyra), meaning "purple". Purple was the colour of royalty, and the Roman "imperial porphyry" was a deep purple igneous rock with large crystals of plagioclase. Some authors claimed the rock was the hardest known in antiquity.
The ideal grade, called "Deep Siberian", has a primary purple hue of around 75–80%, with 15–20% blue and (depending on the light source) red secondary hues. " Rose de France" is defined by its markedly light shade of the purple , reminiscent of a lavender / lilac shade.
It is typically blue, but natural "fancy" sapphires also occur in yellow, purple, orange, and green colors; "parti sapphires" show two or more colors. Red corundum stones also occur, but are called rubies rather than sapphires. Pink-colored corundum may be classified either as ruby or sapphire depending on locale.
It is a mixture of amethyst and citrine with zones of purple and yellow or orange. Almost all commercially available ametrine is mined in Bolivia. The colour of the zones visible within ametrine are due to differing oxidation states of iron within the crystal.
Lapis lazuli (UK: / ˌ l æ p ɪ s ˈ l æ z (j) ʊ l i, ˈ l æ ʒ ʊ-,-ˌ l i /; US: / ˈ l æ z (j) ə l i, ˈ l æ ʒ ə-,-ˌ l i /), or lapis for short, is a deep-blue metamorphic rock used as a semi-precious stone that has been prized since antiquity for its intense color.
The color lavender might be described as a medium purple, a pale bluish purple, or a light pinkish-purple. The term lavender may be used in general to apply to a wide range of pale, light, or grayish-purples, but only on the blue side; lilac is pale purple on the pink side.
Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula Cu Al 6( PO 4)4( OH)8·4 H 2 O. It is rare and valuable in finer grades and has been prized as a gemstone for millennia due to its hue.
Emeralds, like all colored gemstones, are graded using four basic parameters known as "the four Cs": color, clarity, cut and carat weight. Normally, in grading colored gemstones, color is by far the most important criterion. However, in the grading of emeralds, clarity is considered a close second.
The amethyst is a brilliant transparent stone of a purple colour and varies in shade from violet purple to rose. There are two kinds of amethysts: the oriental amethyst, a species of sapphire that is very hard (cf. Heb., hlm ), and when colourless is almost indistinguishable from the diamond .
Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula Cu Al 6 ( P O 4) 4 (O H) 8· 4 H 2 O. It is rare and valuable in finer grades and has been prized as a gem and ornamental stone for thousands of years owing to its unique hue. A turquoise dome of the Po-i-Kalyan Mosque in ...