Synthetic stones are known to have a very regular crystallization, which generally allows the stone to have good strength as well as an evenly distributed coloration. However, during manufacturing process of raw materials, certain elements can cause variations’ color, implying presence of several shades in the finished product. In order to understand color variations in synthetic stones, it is necessary to look at the origin of gems’ coloring.
Origin of gems’s coloring
Color of a stone is generally due to the presence of chromogenic elements, meaning the presence of a certain content of one or more metallic elements(the most common being Iron, Copper, Titanium, Chromium, Manganese, Vanadium, Cobalt, Nickel).
Generally,the higher the concentration of chromogenic elements in a stone, the more coloredor even darker the stone will be. A lower concentration will result in a lighter, less pronounced shade.
Color variation in synthetic stones
The color of a synthetic stone is obtained by implementing the desired concentration of chromogenic elements during the crystallization process. This is a particular challenge requiring excellent precision and rigor in the manufacture of the product.
In the case of synthetic rubies, chromium mainly but also iron and vanadium can vary its shades. When synthetic ruby is in fusion, rough crystallizes little by little from the inside to outside.
The cooling is done very slowly to obtain the best possible quality crystallization, avoiding inclusions and potentially fragile areas. This process allows chromogenic elements to be distributed heterogeneously. This is why outside of synthetic rough is usually slightly darker than the inside layer.
Other criteria that can influence color of synthetic stones are the different manufacturing processes, the crystallization time or desired dimensions.
The creation of synthetic material is still linked to laws of nature. Some of the steps in the formation of natural stones are found in the manufacturing process of synthetic stones, such as the crystallization time and the melting temperature.
However, synthetic processes have brought a high degree of purity and consistency to synthetic materials while allowing them to retain certain shades of color and a chemical composition identical to natural materials.