Garnet
Garnet, birthstone for January, The history of Garnet dates back to the Bronze Age (more than 5,000 years ago), when it was a very popular gemstone. According to Christian and Jewish mythologies, during the Great Flood a radiant red Garnet guided the way for Noah, ultimately leading his ark to salvation. Garnets are available in a wide range of "warm" tones such as reds, oranges, yellows and burgundies, as well as greens and some rare color-change varieties.

Hardness: 7 - 7.5
Specific Gravity: 3.6
Refractive Index: 1.73
Chemical Composition: Mg3Al2(SiO4)3, Magnesium Aluminum Silicate
Crystal Structure: Isometric

Amethyst
Amethyst, birthstone for February, Amethyst's intense purple color and relative availability have ensured its popularity throughout the millennia. A popular gem since Pre-Roman times, the wine-loving Greeks believed amethyst gems could prevent intoxication while medieval European soldiers wore amethyst amulets as protection in battle.

Hardness: 7
Specific Gravity: 2.65 - 2.91
Refractive Index: 1.544 - 1.553
Chemical Composition: SiO2, Silicon Dioxide
Crystal Structure: Trigonal

Aquamarine
Aquamarine, birthstone for March, Aquamarines derive their name from the Latin words for “sea water”. Ancient mariners believed they could placate angry and violent storms from the God of the sea with this gem. Characterized by large sizes, crystal clear transparencies, and blue and seawater-like hues, its no wonder the ancients believed aquamarine was the "the gem of the sea".

Hardness: 7.5 - 8
Specific Gravity: 2.67 - 2.84
Refractive Index: 1.57 - 1.60
Chemical Composition: Be3Al2(SiO3)6, Beryllium Aluminum Silicate
Crystal Structure: Hexagonal

Bloodstone
Bloodstone, birthstone for March, Medieval Christians often used bloodstone to carve scenes of the crucifixion and martyrs, leading it to also be dubbed martyr's stone. The legend of the origin of bloodstone says that it was first formed when some drops of Christ's blood fell and stained some jasper at the foot of the cross. A beautiful example of carved bloodstone with the seal of the German Emperor Rudolf II can be seen at the Louvre museum in Paris.

Hardness: 7
Specific Gravity: 2.65 - 2.66
Refractive Index: 1.543 - 1.552
Chemical Composition: SiO2 - Silicon Dioxide

Diamond
Diamond, birthstone for April, The normal range of colors in diamonds run from colorless to slightly yellow or brown. "Fancy colors" are those colors outside the normal range, and are found in all colors. The most sought after are colorless, and the more intense "fancy colors", blue, pink and red. Red diamonds are among the rarest of all gemstones, only two are known to exist.

Hardness: 10
Specific Gravity: 3.52
Refractive Index: 2.42
Chemical Composition: C, Elemental Carbon
Crystal Structure: Isometric

Emerald
Emerald, birthstone for may, Originally mined at Queen Cleopatra's Ancient Egyptian emerald mines, the "green fire" was so highly valued in the Middle Ages that Spanish Conquistadors embarked on notorious campaigns to find the location of South America's legendary emerald mines. With bright vivid green colors that are unmatched by any other gem, continues to be one of the world's most desirable gems.

Hardness: 7.5 - 8
Specific Gravity: 2.67 - 2.84
Refractive Index: 1.56 - 1.59
Chemical Composition: Be3Al2(SiO3)6, Beryllium Aluminum Silicate
Crystal Structure: Hexagonal

Alexandrite
Alexandrite, birthstone for June, Discovered in Russia’s Ural Mountains on the birthday of Czar Alexander in 1830, Alexandrite is one the most valuable gem types in the world. Known for it’s miraculous and chameleon like color changes from red to green, the gem is admired and coveted by all gemstone connoisseurs the world over. A valuable form of the mineral chrysoberyl, alexandrite is sourced from Madagascar,Tanzania, India, Sri Lanka as well as the old classical Russian deposits.

Hardness: 8.5
Specific Gravity: 3.5 - 3.8
Refractive Index: 1.745 - 1.757
Chemical Composition: BeAl2O4, Beryllium Aluminum Oxide
Crystal Structure: Orthorhombic

Pearl
Pearl, birthstone for June, Aphrodite's tears of joy, dew drops filled with moonlight, Krishna's wedding gift to his daughter and Cleopatra's love potion, the legends abound but one fact is undeniable, pearls are the oldest known gem and for centuries were considered the most valuable. So valuable that the Roman General Vitellius allegedly financed an entire military campaign with just one of his mother's pearl earrings. Believed to symbolize the moon, the oldest known pearl jewelry is a necklace found in the sarcophagus of a Persian princess who died in 520 BC.

Hardness: 2.5 - 4.5
Specific Gravity: 2.68 - 2.85
Refractive Index: 1.53 - 1.69
Chemical Composition: Calcium Carbonate with Water and Conchiolin

Moonstone
Moonstone, birthstone for June, Extremely well known, moonstone is said to possess mystical qualities including balancing yin & yang, symbolizing the sacred Third Eye, clarifying spiritual understanding, providing protection against epilepsy or sunstroke, a cure for headaches or nose bleeds and ensuring a high yield in crops. While the Romans thought it formed from moonlight, "adularescence" actually produces the iridescent sheen that makes moonstone the most valuable variety of feldspar.

Hardness: 6 - 6.5
Specific Gravity: 2.64 - 2.68
Refractive Index: 1.533 - 1.552
Chemical Composition: NaCa(Al, Si)AlSi2O8, Sodium Calcium Aluminum Silicate
Crystal Structure: Monoclini

Ruby
Ruby, birthstone for July,The word for ruby derives from the Latin term "Rubeus", meaning the red. Rubies of a top quality are more rare and more valuable than diamonds? Hardly a month has passed in the last 60 years without new diamond deposits being discovered – something that definitely cannot be said about rubies, which are mined only in a handful of locales worldwide! So enchanted were the ancient Hindus by rubies, they considered them to be "Ratnaraj", or the "King of Precious Stones".

Hardness: 9
Specific Gravity: 3.9 - 4.1
Refractive Index: 1.76 - 1.78
Chemical Composition: Al2O3, Aluminum Oxide
Crystal Structure: Trigona

Peridot
Birthstone for August and the gem for Librans, peridot is the gem variety of olivine that exhibits golden lime-greens. Known as the "Gem of the Sun" to the Ancient Egyptians, peridot was a favorite gemstone of Cleopatra and was often mistaken for emerald. The pronunciation of this very popular gem is often confused and should be pronounced pair-ee-doh, not pair-ee-dot.

Hardness: 6.5 - 7
Specific Gravity: 3.31 - 3.48
Refractive Index: 1.630 - 1.695
Chemical Composition: (Mg, Fe)2SiO4, Magnesium Iron Silicate
Crystal Structure: Orthorhombi

Sapphire
Sapphire, birthstone for September, Prized since ancient times, sapphire has been called the "gem of the heavens". Ancient people believed that the power of wisdom is contained within this precious gemstone, enabling the wearer to find the correct solution to challenging obstacles. Sapphires come in all spectrums of color, except for red. Often when people simply refer to sapphires, they mean blue sapphires. Other color sapphires are correctly referred to as fancy sapphires.

Hardness: 9
Specific Gravity: 3.9 - 4.1
Refractive Index: 1.76 - 1.78
Chemical Composition: Al2O3, Aluminum Oxide
Crystal Structure: Trigonal

Tourmaline
Tourmaline, birthstone for October, A gem with balancing powers, tourmaline is one of the birthstones for Librans everywhere and is believed to foster inner harmony while bringing balance to both individuals and relationships. The favorite of Dowager Empress Tzu Hsi, Tourmaline is known as the "Chameleon Gemstone" for its myriad of stunning colors. A wonderfully affordable gem variety, tourmaline also boasts a colorful and romantic history.

Hardness: 7 - 7.5
Specific Gravity: 3.0+
Refractive Index: 1.62 - 1.68
Chemical Composition: Na(Li,Al)3Al6Si6O18(BO3)3 (OH)4, Sodium Lithium Aluminum Boro-Silicate Hydroxide
Crystal Structure: Trigonal

Opal
Opal, birthstone for October, is usually thought as an Australian-origin black, white, or palish colored gem that exhibits a myriad of iridescent colors. What many don’t realize is that opal is actually an incredibly diverse gem type that doesn’t always have this iridescent effect! Cherry colored specimens that rival ruby, fiery-orange opals that sparkle like spessartite, tropical blue gems just as intense as larimar, and even deep gorgeous pinks are found in numerous locations around the world!

Hardness: 5.5 - 6.5
Specific Gravity: 1.42 - 2.25
Refractive Index: 1.37 - 1.47
Chemical Composition: SiO2-nH2O, Hydrated Silicon Dioxide

Topaz
Topaz, birthstone for November,The name Topaz is believed to have come from either the Island of Topazios in the Red Sea or from the Sanskrit word "topas" meaning "fire". Alongside peridot, the Egyptians called topaz the “gem of the sun”, believing it was colored by the golden glow of the sun god Ra and was a powerful protector from harm. The Romans also associated topaz with their sun god and felt this gem could dispel enchantment and improve eyesight, while the Ancient Greeks thought it could increase strength and render one invisible in times of danger.

Hardness: 8
Specific Gravity: 3.4 - 3.5+
Refractive Index: 1.61 - 1.64
Chemical Composition: Al2SiO4(F,OH)3, Aluminum Silicate Fluoride Hydroxide
Crystal Structure: Orthorhombic

Citrine
Citrine, birthstone for November,Citrine derived its name from the old French word for lemon, citrin. The Romans were the first people to utilize its resplendent yellow colors in carvings and cabochons in the first century A.D. In later times citrine was used as a protective talisman against the plague, evil thoughts, charms against snakebites, and was also believed to symbolize happiness, aid digestion and remove toxins from the body. Noted for bright yellow colors, high clarities and large sizes, citrine is sometimes produced by heating amethysts!

Hardness: 7
Specific Gravity: 2.65 - 2.91
Refractive Index: 1.544 - 1.553
Chemical Composition: SiO2, Silicon Dioxide
Crystal Structure: Trigona

Tanzanite
Tanzanite, birthstone for December, is America's #2 selling colored gem after blue sapphire With captivating bright blue colors, tanzanite's quality and price make it a jewel that other gems just cannot compete with! Discovered in the 1960's, tanzanite is relatively new to the jewelry world. Legend says Masai cattle herders on East Africa's savannah plains discovered the gem after lightning strikes revealed brilliant blue jewels. The world's only source of tanzanite is the deposits in Tanzania, East Africa.

Hardness: 6 - 7
Specific Gravity: 3.2 - 3.4
Refractive Index: 1.69 - 1.70
Chemical Composition: Ca2Al3(SiO4)3(OH), Calcium Aluminum Silicate Hydroxide
Crystal Structure: Orthorhombic

Zircon
Zircon, birthstone for December, Zircons first came to note in the ancient Indian tale of the Kalpa Tree, where a votive offering made to the Gods was a bright glowing tree with bejeweled leaves of green zircon. The name "Zircon" is believed to have derived from the Arabic words, "zargun", meaning golden-color. Despite this color associated name, zircon actually occurs in virtually all colors. No relation at all to cubic zirconia, zircon is a bright, lustrous, highly brilliant gem, that occurs in large sizes with high clarities, making it a favorite amongst people who like bright colorful gems.

Hardness: 7.5
Specific Gravity: 4.6 - 4.7
Refractive Index: 1.92 - 2.01
Chemical Composition: ZrSiO4, Zirconium Silicate
Crystal Structure: Tetragonal