Nephrite jade is an ornamental stone used in carvings, beads, or cabochon cut gemstones. For gemstone use, most opal is cut and polished to form a cabochon. Another find was a small gemstone, a cabochon (polished) sardonyx. This method works well for either the cabochon or faceted stones. The relative non-uniformity motivates the cutting of emeralds in cabochon form, rather than faceted shapes. There are two general types of gemstone cutting&colon; cabochon and facet. This effect is best seen in gemstones cut in cabochon form perpendicular to the c-axis. Two of the sapphires used are cabochon cut and the rest are brilliant cut. Queen Mary had the tiara altered to accommodate 15 of the Cambridge cabochon emeralds. There are three broad categories of lapidary arts&colon; tumbling, cabochon cutting, and faceting. On the top of this cross is a cabochon ruby. Gems are usually given a cabochon cut to best display their chatoyance. Among these multi-hued jewels, cabochon cuts were another innovation. Other forms are possible&colon; the octagon combined with a cabochon, a star, a cross, etc. The head is crowned by a laurel wreath with a cabochon in its centre.