Page 36 - November 17, 2025 - Term Sheet & Compliance Package - Black Mountain Global Group - english

USE OF CREDIT

In the further brilliant cut, the gemstones are a special shape with numerous cut facets to achieve exceptional brilliance. The shape resembles a cone and ensures

maximum light penetration at the tip of the diamond.

The most common treatment method used for corundum, i.e., ruby, is heat treatment. Almost all corundum available in the jewelry trade has been treated this way.

Two types of firing are distinguished: Low-temperature treatment preserves inclusions of minerals that are not corundum. In the case of RUBY, this is mainly rutile,
whose crystals are not melted. The low-temperature treatment is up to approximately 1,100 degrees Celsius, since the rutile begins to melt at around 1,200–1,350

degrees Celsius.

The temperature, the duration of the temperature, the atmosphere during heating, as well as the chemical structure of surrounding or jointly fired materials all influence

the result of the heat treatment.

Heat treatment between 1,100 and 1,800 degrees Celsius can remove unwanted brown, violet, or purple hues from rubies. Extended firing of rubies between 1,450 and
1,750 degrees Celsius, followed by rapid cooling, can also remove unwanted "rutile silk." After firing, the treated ruby appears purer to our eyes than before.

Since the 1990s, rubies have been thermally treated together with chemical additives. This improves both color and transparency. Our experts often use a melt of borax,

quartz, and other chemical additives, in which the ruby is heated for 10 to 20 hours. The borax melt also penetrates cracks and fractures, filling fissures in the ruby and

improving transparency.