Gemstones are defined as any mineral or naturally occurring substance in a in a raw state that is capable of being turned into a gem. There are many different kinds of gemstones with diamonds being the most well known of all the different varieties. The value of a gemstone depends largely on its type as well as its condition and size. Many gemstones are also considered crystals, a crystal is any three dimensional form that a given mineral exhibits. Gemstones and crystals are widely used to make jewelry, and many other ornamental pieces, and many crystals and gemstones are said to have healing powers.

Quartz Crystal – a beautiful, naturally occurring crystal, quartz is the second most abundant mineral found in the Earth's crust. There are many varieties of quartz crystal.

Citrine is a quartz crystal with a color ranging from light yellow to almost brown.

Rose Quartz is normally anywhere from a pale pink to a beautiful rose red color.

Amethyst is the most popular and well known of all quartz crystals and can be many different shades of purple.

Milky Quartz is the most commonly found variety of crystal quartz, and gets its cloudy appearance from liquid or gas trapped during the formation of the crystal.

Ruby – known for its bright fiery red color, luster, hardness, and rarity. Large sized transparent rubies are even more rare than diamonds. In order for a ruby to possess any value it must be transparent, as semi-opaque rubies are of little value.

Opal – known for its iridescent color that changes with the angle that the stone is viewed, opals are the most colorful of all gems, and the flashes of changing color is referred to as opalescence. The intensity of the different colors in an opal determines its value.

Topaz – a gemstone that can be almost all colors and the most valuable is “imperial topaz” which is a golden yellow-orange color. Topaz is often thought of as a light blue gem but it wasn't until fairly recently that blue topaz became popular. Natural blue topaz is extremely rare in nature and most blue topaz gems are actually clear gems that were heat treated.

Emerald – the favorite and most famous of all green gemstones. Emeralds are a beautiful green color and because of their durability and rarity, they are one of the most valuable gemstones. Emeralds are known to have flaws and it is extremely rare to find a flawless stone.

Diamond – the most brilliant and well known of all gemstones, diamonds are the hardest substance found on Earth. The most popular diamonds are clear, and are far more valuable than tinted or colored diamonds, however recently yellow diamonds have gained popularity.

Garnet – gems which are often thought of as dark red in color however garnets have great color variation and all colors of gems are cut from garnet with the exception of blue.

Silver – one of the most famous precious metals, silver is often used for ornamental pieces. Silver is very malleable and easy to work with but tends to bend easily so it is often alloyed with other metals. The most common silver used in jewelry making is sterling silver, and silver jewelry is much less pricy than gold.

Gemstone Production – an overview of the production of certain US gemstones

GIA – the Gemological Institute of America offers information on all types of gems, educational programs, reports and services, and research and resources

Crystal Therapy – all about the use of gemstones and crystals for healing and therapy

Famous Gemstones – information on some of the world's most famous and well known gemstones

International Gem Society – offers information on gemology courses, resources on grading and technical articles on gemstones