Precious gemstones
Ruby, sapphire, emerald and other colored gems: what they are and how to wear them.
15 entries
Materials
Alexandrite
Alexandrite shifts from bluish green to purplish red depending on the light; a very rare and costly gem (8.5 on Mohs), and a June birthstone.
Materials
Aquamarine
Aquamarine is blue-green beryl (7.5-8 on Mohs), from the same family as emerald; transparent and brilliant, it is the March birthstone.
Buying guides
Carat of gems and karats of gold: not the same thing
Carat measures the weight of gems, 0.2 grams; karats of gold measure its purity out of 24 parts. Explanation and chart.
Materials
Emerald
What an emerald is, its types by origin (Colombian, Zambian, Brazilian, trapiche), meaning, hardness, treatments and care.
Techniques
Gemstone faceting
Faceting cuts a gem with polished flat surfaces (facets) arranged to reflect light; the faceting machine, angles, indexing and polishing.
Materials
Gemstones
Precious and semi-precious gemstones in jewelry: the difference, types, Mohs hardness, care and a guide to the most used gems.
Jewelry care and maintenance
How to clean jewelry with gemstones
How to clean jewelry with stones: which stones handle water and a brush, which are delicate (pearls, opal, emerald, turquoise) and which avoid ultrasonic.
Buying guides
Jewelry terms from A to Z
A glossary of over one hundred jewelry terms explained in a few words: metals, gems, techniques, tools and parts of a jewel, with links to each topic.
Materials
Ruby
Ruby is the red variety of corundum, a very hard gem (9 on Mohs) colored by chromium; it is valued for its color, clarity and origin.
Materials
Sapphire
Sapphire is corundum in any color except red, famous for blue; very hard (9 on Mohs), it is ideal for engagement rings and everyday wear.
Materials
Spinel
Spinel is a hard gem (8 on Mohs) in vivid colors, famous for having been mistaken for ruby for centuries; suitable for everyday wear.
Materials
Topaz
Topaz is a hard aluminum silicate (8 on Mohs) with easy cleavage; blue topaz is usually treated. The November birthstone.
Materials
Tourmaline
Tourmaline is a family of gems in every color (7-7.5 on Mohs), with varieties such as watermelon and Paraíba; it is the October birthstone.
Materials
Tsavorite
Tsavorite is an intense green garnet (7-7.5 on Mohs) from Kenya and Tanzania, very brilliant and almost free of inclusions; an alternative to emerald.
Jewelry
Types of gem and diamond cuts
A catalog of the most common gem and diamond cuts: brilliant, princess, emerald, Asscher, radiant, cushion, oval, pear, marquise, heart, baguette and cabochon.