Garnet is isotropic and has no polychromatic color, while ruby has obvious polychromatic color. Under ultraviolet light, ruby has red fluorescence, while garnet is inert. Magnified observation shows that the interior of garnet is clean, and there are abundant gas-liquid inclusions and solid inclusions in ruby.

Spinel is isotropic, polychromatic and has a lower refractive index than ruby. After amplification, it has octahedral negative crystals arranged in a beaded pattern.

Under the illumination, the spherical gem will show a flashing light band (swimming color), just like the cat's eyes, so it is called opal, because the mineral contains dense and fine parallel fibrous and needle-like inclusions (the light band is perpendicular to the inclusions). Due to the scattering of light, the white light deviates from the original direction, and then it is converged by the curved surface to appear as a "cat's eye".

Extended data

There are many kinds of garnet, among which garnet and garnet are called garnet and belong to common garnet varieties. Very few inclusions, if any, are mostly round or irregular contour crystals, while garnet has no cleavage, and its fracture is shell-shaped and even uneven. Ruby is distributed in volcanic rocks and alluvial deposits, so its crystal is not large, so it is often seen to be made into rings or embedded in small pendants.

From the appearance, the color of spinel may be bright red like ruby, but it tends to be brick red or even orange more often; It can also have a purple hue, which was found in Afghanistan and was once called "ballas Ruby". Red spinel is soft in color, pink but not red, with good luster and transparency. It is processed into elliptical or circular mixed facet cutting, or square or rectangular step cutting.

Baidu Encyclopedia-Ruby

Baidu encyclopedia-red spinel

Baidu encyclopedia-curve gem

Baidu encyclopedia-garnet