Properties of Garnet, Ruby and Moonstone gems
Garnet is the January birthstone. It is a semi-precious group of silicate minerals that has similar physical and chemical properties. Its name is derived from the Latin word “granatus” meaning grain; it refers to the nature of its occurrence where the minerals look like seeds or grains. It dates back to ancient Egypt towards the end of the Bronze Age. The gem is normally associated with ultramafic igneous rocks and usually found within metamorphic rocks. Garnet gems normally come in red color. It can also come in a wide range of colors such as green, magenta, golden brown, orange and yellow. The gem contains a high amount of vanadium which enables it to change color under different visible lights. Under any incandescent light, a garnet appears purple. It looks bluish green in daylight.
Ruby is the July Birthstone and is normally found in Myanmar, Sri Lanka, Thailand, Afghanistan, Madagascar and Tajikistan. It belongs to the mineral family Corundum and is the hardest gemstone in the world after diamond. It scores 9.0 in hardness on the Mohs scale of mineral hardness. Ruby generally comes in all shades of red and pink. Just like many colored gemstones, the hue, saturation and tone of its color are important factors in determining its value. In the United States, it must meet a minimum color saturation to be considered a Ruby. It is otherwise called a pink sapphire. The gem also exhibits the pleochroism phenomenon which makes it appear either yellow-red or deep red when viewed from different angles.
Moonstone is a semi-precious gem normally found in Brazil, Madagascar, Russia, Tanzania, Australia, India, Myanmar, Sri Lanka and USA. Its name is derived from the Greek word “Selenite” which means “goddess of the moon”. It occurs in syenite pegmites and granitic as an important rock-forming component. A moonstone can either be translucent or opaque. Its characteristic white/blue scheen is attributed to “the shiller effect” which causes a bluish, milky glow to radiate from inside the gem. When the light source is moved or the gem is turned, the Schiller appears to move. A white Schiller is the most common effect on a moonstone. Blue or orange Schiller is seen in rarer specimens.