The uncut original gem is a very small stone with a rugged appearance. It needs to be cut and polished before it can become our common multi-faceted gem. If the polishing is not done well, there will still be pits on the surface.
As for whether it is true or not, it is more troublesome to test. The general test contents are as follows:
Refractor: Different gemstones have different mineral compositions and different refractive indexes. The refractive index of sapphire is between 1.762- 1.770.
Microscope: Look at the inclusions in the gem. Generally, sapphire has obvious growth lines and bands, and rutile inclusions.
Spectroscopy: looking at the absorption band of gemstones with a spectroscope.
Hardness ratio: to test the hardness of jewelry, but it may be harmful to gems, so it is generally not used. The hardness of sapphire is 9, second only to diamond and silicon carbide.
Polarizer: judging isotropic body, anisotropic body, crystal aggregate, birefringence, etc. Sapphire has birefringence of 0.008 ~ 0.010; Uniaxial crystals have negative optical properties. In some cases, they have abnormal biaxial crystals.
Ultraviolet lamp darkroom: check the fluorescence characteristics, and the partially heated sapphire has fluorescence reaction.
Because most people don't have professional tools, I suggest you go to the testing center for testing. Provincial capital cities will have such units.