Only experts can distinguish between natural and synthetic, lab-created Ruby. The process of creating synthetic Ruby is known as the Verneuil process. Despite this, Ruby is still subject to chipping and fracture if handled roughly, and care should be taken to ensure it is properly handled. Ruby is a tough and durable gem, and the only natural gemstone harder than Ruby is Diamond. Ruby is also pleochroic, and will sometimes display a lighter and more intense color

These impurities are often responsible for causing a Ruby to fluorescent, which can be helpful in its identification. The color of Ruby is usually caused by minute inclusions of the metal chromium. A unique gemstone form composed of opaque red Ruby in contrasting green Zoisite is well known from Tanzania, and is used as a minor gemstone and can be carved into ornaments. Though Ruby can be one the most expensive gemstones, it also comes in more dull opaque forms that are fairly inexpensive, and are often polished into cabochons. The same Rutile inclusions that are responsible for asterism in certain Rubies can also decrease transparency and cause a hazy effect known as silk. Rubies have relatively little value, even if they display asterism. Rubies must be have good transparency to possess gem value. Star Rubies exists in six ray stars, though twelve ray stars are also known.

A Ruby displaying asterism is known as a ' Star Ruby', and if transparent can be very highly prized. Inclusions of tiny, slender, parallel Rutile needles in Ruby cause a polished gem to exhibit asterism. Heat-treating a Ruby can also increase its transparency by removing tiny internal flaws. Many Rubies on the market are from Thailand, and these Rubies have a less-desirable brownish hue, though they often can be heat treated to improve color. However, Burmese Ruby rarely exceeds several carats large flawless Burmese Rubies can be worth millions of dollars. Ruby from Burma is famous for its exceptional coloring, and has traditionally produced the finest Rubies. Such Ruby is known as ' Burmese Ruby' or ' Pigeon's Blood Ruby'. The most preferred color is a deep blood red with a slightly bluish hue. The color of Ruby ranges from bright red to dark reddish-brown.

Ruby sapphire