This method has a long history, its result is stable, lasting and universally accepted. Mainly used in:
1 cut blue:
In the high temperature oxidation atmosphere heating with bluish ruby or dark sapphire, will occur in Fe2 + to Fe3 + shift, so that the sample of Fe2 + / Ti4 + color causing ions to decrease in number, thereby removing the excess blue. This method can also be light yellow, orange or yellow green sample into a golden yellow.
2 deepen or induced blue:
In the high temperature and reducing atmosphere heating Light Sapphire gem, the original Fe3 + to Fe2 +, an increase of Fe2 + / Ti4 + coloration ions on the quantity, make the sample from shallow to deep.
3 removing filamentous inclusions:
In the air, ruby or sapphire heating to 1600-1800 C, so that the original, with filiform needle inclusions existed in the form of rutile ( TiO2 ) melt, then cooled rapidly, making titanium into the lattice with Al2O3 to form solid solution, so as to improve the clarity of purpose.
The 4 generation of stars:
When heated in air samples, and then slow cooling, so that the sample to form a solid solution of titanium melting, forming a needle-like inclusions of rutile, resulting in starlight.
5 healing of fracture:
Will develop plenty of cracks ruby in heating due to sodium borate, sodium borate can reduce the melting point of the ruby, fracture healing.
Heat treatment of differential:
1 color appears inhomogeneous diffusion halo or color swatch.
2 contains a low melting point inclusion ( such as feldspar, calcite, apatite ) occurrence of partial melting, so that the original columnar crystal edge becomes smooth.
Some filamentous, needle-like inclusions ( such as rutile ) into intermittent filamentous, punctate.
In 3 samples from the interior of primary fluid inclusions in high temperature under the effect of splitting, fluid into a new burst fractures.
The 4 has been cut a good sample surface will have partial melting, producing some rugged pockmarks. In order to eliminate the pit and the second polishing, often appear double girdle, faceted girdle phenomenon.
5 after heat treatment to produce a yellow and blue sapphire deletions of the 450nm absorption band.
Surface diffusion treatment
High temperature so that the coloring ions into the pale or colorless sample surface lattice, forming a thin colored diffusion layer. The thickness of the general 0.004-0.4mm. Cr to do with coloring agent can be generated when the red diffusion layer; Fe, Ti coloring agent can be generated when the blue diffusion layer; Cr, Ni coloring agents can produce orange-yellow diffusion layer.
1 when the sample is soaked in two methyl iodide in observation, visible to the color concentrates more on the waist, facet edge and open fractures.
2 in the short-wave ultraviolet surface diffusion sapphire can see chalky blue or green fluorescence, and the surface diffusion treatment of ruby can see patchy white and blue phosphor.
The 3 surface diffusion ruby with abnormal refraction, refraction rate of up to 1.80.
The 4 surface diffusion treatment of samples of two color fuzzy, red variety sometimes manifested as abnormal yellow – brown two color.
The 5 surface diffusion treatment of the starlight varieties, the star line perfect, uniform, rather like synthetic starlight varieties, but microscopic observation can be found” starlight” confined to the surface of the sample. Moreover, no stars of natural varieties in the three groups of aligned rutile needles, only the surface consists of a thin layer of floc, they are composed of small white spots come together and form.