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Red Stones
Red Stones can be classified into several groups and sub-groups. All these have their different identical properties. These are the five major type of red stones which have been given below:RUBY
Chemical Structure: Al2O3::Cr
Mineral Name: Corundum (Aluminum Oxide with Chromium)
Hardness: 9.0
Refractive Index: ~1.762-1.770
Specific Gravity: 4.0
Ruby is the most important red stone in the Red Stone family. These gemstones have red color which have different hues that varies from light pink to blood red. They have ultraviolet fluorescence effect due to which under long waves these appear red in color. What ever the color they have are due to the presence of Chromium. The prime sources from where these gemstones are found are Australia, Sri Lanka, Greenland, in some African countries, North & South Carolina, Myanmar and Madagascar. In Myanmar, Ruby gemstones have a trade name "Mogok". Among all natural stones, Ruby is the second hardest stones just after Diamond. In natural form, these stones contain several impurities including color imperfections.
GARNET
Chemical Structure: X3Y2(SiO4)3
Harness: 6.0 to 7.5
Specific Gravity: 3.1 to 4.3
Refractive System: 1.72 - 1.94
Optical Properties: Single refractive, often anomalous double refractive.
Color: virtually all colors
Luster: glassy to pitchy
Crystal System: Isometric
Cleavage: None
These Garnet gemstones are found in different colors including yellow, red, orange, purple, blue, pink, black and even these may be colorless, but the most prominent color of these stones is red. The rarest color is blue. Countries where these stones are found are Turkey, U.S.A, Madagascar and Russia. The color of these stones change according to the changing light, for instance the bluish green color of these stones changes into purple color in incandescent light.
ZIRCON
Chemical Structure: ZrSiO4
Mineral Name: Zirconium Silicate.
Refractive Index: 1.967 - 2.015
Specific Gravity: 4.6 to 4.7
Hardness: 7.5
Color: brown, red, yellow, green, black, and colorless.
Crystal System: Tetragonal.
Cleavage: Indistinct, two directional.
Luster: Relentless.
Zircon gemstones are fluorescent in nature. These stones are incurred in sedimentary and metamorphic rocks. Large crystals of these gemstones are not often found abundantly. They are found in different colors including yellow, brown, black, red, green and even colorless. In those Zircon stones which are below the gems quality, on heating them their color can be changed. Depending upon the requirements, the color can be altered by applying heat treatment. Noted occurrences of these gemstones are in the Ural mountain (Europe), U.S.A, India, Italy, Sri Lanka, Cambodia, Thailand, South Africa, Canada and Madagascar.
SPINAL
Chemical Structure: MgAl2O4
Color: Varies from red to blue to mauve, dark green, brown, black etc
Refractive index: 1.712-1.762
Hardness: 8.0
Specific gravity: 3.54-3.63
Crystal System: Isometric
Cleavage: Indistinct.
White perpendicular streaks run across the gemstones. Noted occurrences of these gemstones are in Myanmar, Sri Lanka, Thailand. The red transparent spinals are very much resembling to rubies and therefore, these are referred as "Spinal Rubies". Rubicella is another kind of spinal gemstone.
TOURMALINE
Chemical Structure: (Ca,K,Na,[])(Al,Fe,Li,Mg,Mn)3(Al,Cr, Fe,V)6 (BO3)3(Si,Al,B)6O18(OH,F)4.
Hardness: 7.0 to 7.5
Dispersion: 0.017
Refractive Index: 1.635 to 1.675
Specific Gravity: 3.0 to 3.26
Density: 2.82 - 3.32
Color: Most common color is blackish red to light red, other colors are violet, brown, pink, green, in the dual colored green and pink.
Crystal system: Trigonal
Cleavage: Indefinite.
Fracture: Uneven, small conchoidal, brittle
Luster: Glassy, sometimes pitchy.
