Gemstone Improvement Techniques

Artificial ways of beautifying jewels are known from ancient times. As early as the first century AD er Guy Pliny the Younger stated that he had studied many works of scientists, his predecessors, when he decided to collect all the necessary information about the nature of precious stones. The methods by which stones were then processed are not so different from modern methods of refining precious stones. Emperor Diocletian (300 AD) was so against artificial refinement of jewels that he ordered the destruction of all the books where it was described how to do it. This decree, of course, was executed with a certain degree of success, and a lot of books burned down, but the resourcefulness of the human mind helped the described methods not only survive, but also improve.

In the distant past, wanting to get the maximum value of a stone as high as possible, the cutter himself was engaged in ennobling stones. Today, there are centers such as Bangkok in Thailand that specialize in processing both finished and untreated stones. Heat treatment of corundum (ruby and sapphire) is an excellent example. With this treatment, corundum can simply be subjected to heat, as well as using heat along with treatment (filling cracks, voids with special materials or treatment with beryllium atoms (Be heated)).

Refinement and price

There are some stones that could not exist without refining. For example, by heating amethysts, you can get beautiful shades of citrine: bright yellow, golden, intense reddish-orange “Madeira” citrine. In nature, such citrines are also found, but very rarely. Their price will be much higher.

In connection with the growth in demand, tanzanites increasingly began to be subjected to heat treatment to get rid of brownish shades in the shadows, and show more violet and blue shades.

Pink topaz– another example of a stone that cannot be accessed without heat treatment. Refinement in this case is not that acceptable, it is necessary that topaz with this color can be created.

Increased interest in sapphires and rubies, increased the cost of the non-refined material by 50-100%. Does this mean that such stones are more beautiful? NOT! In most cases, beautification makes the stone more attractive. And the final price, which is not small, is a reward for beauty and for the fact that the stone itself was rare, even if it was not sanitized.

What you have just read about is just the tip of the iceberg. The following article will list the main methods of refining and their application in more detail.


In the XVI century, it was considered absolutely normal and legal that yellowish diamonds were inserted into jewelry, placing purple or blue metal foil under them. At the same time, the yellow stones looked like brilliant white diamonds. Under sapphire, ruby ​​and garnet cabochons, pieces of foil, plate glass and various bright details of butterfly wings, peacock feathers and silk fabrics were also enclosed. Sometimes intersecting rows of parallel lines were scratched on a foil lining — this was necessary in order to fake a star effect. Nowadays such tricks are not approved. Lining can be seen on state jewelery and antique jewelery.


Some varieties of black coral can be given a beautiful golden color if bleached in hydrogen peroxide. The surface of the bleached material can be both smooth and uneven, but in any case it will differ from the whole dug surface of a natural gold coral. Ivory is another material that often undergoes bleaching with hydrogen peroxide or a stain remover. It is bleached to make it lighter. It also almost always erases the greenish tones and rare dark spots of conchiolin from cultured and natural pearls. For this, a combination of hydrogen peroxide and sunlight is used. The brown tiger eye can be brightened to honey with chlorine bleach and saturated oxalic acid.


Covering gems with any varnish is an unacceptable form of processing. But sometimes they do it, especially with coral, lapis lazuli, rhodonite, sugilite and turquoise. Applying mascara is another bad way to improve the look of the stone. The yellow tint in this case is removed if you put a little blue or purple ink on the girdle of the diamond or on the inside of the clips that hold it. A little bluish material, which is used for a protective coating, is sometimes applied to the lower part of yellow diamonds, and then they appear white when viewed from above.

The color of the stones and the special effects of light interference can be influenced by pasting a thin film on the stones. This is done with quartz and topaz, both with crystals and with faceted stones. Topaz coated with vapor deposition can come in a variety of colors. The most popular shades are “amethyst”, “emerald” and “rubellite”. There are various types of metallic coatings. This is a transparent ultra-thin gold film, and a titanium coating that plays with all the colors of the rainbow. Such coatings are very thin, so they wear out quickly and lose their attractiveness. Metallic-coated stones should be stored in separate, sealed packages and handled with care.

Surface diffusion

The process, known as surface diffusion, dramatically improves the color of pale and almost colorless sapphires. Faceted stones are placed in a crucible filled with oxides of aluminum, titanium and iron. When this crucible is heated to high temperatures, the molecules of titanium and iron oxides penetrate into the crystal lattice of corundum. In this case, the stones are almost always noticeably damaged, and they need to be re-polished. The color of the strongest of all is manifested along the edges of the edges and around the girdle. This is how a characteristic “spider” pattern appears, which we can see by examining a stone processed by surface diffusion by the immersion method. Repeated polishing can completely remove colored areas from certain edges, producing “holes in color”, a typical side effect of surface diffusion. Finally Healing Crystals is the best option for you.