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Females: The upper forewing has a yellow discal patch above the blue area. The upper hindwing blue area is small and reduced to discal quadrate spots in 3 and 4. The females resemble those of the common gem (P. hewitsoni) but with yellow spots on the upper hindwing. The males of the blue gem are bluer than the common gem which is greener. [4]
Clarity grading in coloured gemstones is based on the eye-clean standard, that is, a gem is considered flawless if no inclusions are visible with the unaided eye (assuming 20/20 vision). [29] The Gemological Institute of America classifies tanzanite as a Type I gemstone, meaning it is normally eye-clean.
Blue, unbanded fluorite occurs in many localities around the world. Within the UK, blue fluorspars are also found in County Durham, especially Weardale. [1]: 39 Elsewhere, blue fluorspar is known in the Ardennes region of Belgium; the Cave-in-Rock area of Illinois in the United States; [1]: 39 and at various localities in Mexico and China.
Larimar is the tradename for a rare blue variety of the silicate mineral pectolite found only in Dominican Republic, around the city of Barahona. [4] Its coloration varies from bluish white, light-blue, light-green, green-blue, turquoise blue, turquoise green, turquoise blue-green, deep green, dark green, to deep blue, dark blue and purple, violet and indigo and the larimar can come in many ...
Celestine (the IMA-accepted name) [6] or celestite [1] [7] [a] is a mineral consisting of strontium sulfate (Sr S O 4).The mineral is named for its occasional delicate blue color. ...
Asterism on the surface of a blue star sapphire. A purple-pink star sapphire displaying asterism in a platinum ring.. An asterism (from Ancient Greek ἀστήρ (astḗr) 'star' and -ism) is a star-shaped concentration of light reflected or refracted from a gemstone.
The Hope Diamond is a 45.52 carats (9.104 g; 0.3211 oz) diamond that has been famed for its great size since the 18th century. Extracted in the 17th century from the Kollur Mine in Guntur, India, [1] [2] the Hope Diamond is a blue diamond.
"Yogo sapphire" is the preferred term for gems found in the Yogo Gulch, whereas "Montana sapphire" generally refers to gems found in other Montana locations. [18] More gem-quality sapphires are produced in Montana than anywhere else in North America. [18] Montana sapphires come in a variety of colors, though rubies are rare. [16] [18] [23]