Spectrolite has a hardness of 6 to 6.5 and a specific gravity of 2.70. A spectroscope is an instrument that is used to identify gemstones . Spinel ranges in color from red to black to yellow, frequently resembling rubies . Iron and chrome are components of spinel, giving it its color. Spinel belongs to the feldspar species and is found in in Burma, Sri Lanka and Thailand.
Spinel is also laboratory synthesized.
Spinel has a hardness of 8, a specific gravity of 3.58-4.06, and a refractive index of 1.72. A tiny spring keeps the arm of this clasp closed. It is used to attach two other rings or links of a necklace or bracelet . The spring ring was invented early in the 1900's. Jewelry made prior to 1900 or so will not have a spring ring clasp.