When casting with diamonds it is imperative to use a liquid additive such as "Pro- Tech:D or to coat the tree with a special investment such as "SRS Stonecast". It is important to comply strictly to the manufacturer's mixing instructions.
It is not essential to use additives or special investments for stones such as rubies, sapphires, garnets, tourmaline, etc., although this improves the quality of the casting.
It is not advisable to use these special products which contain boric acid with cubic zirconia stones, as they impair their shine.
De-Waxing
It is advisable to use steam de-waxing before placing the flasks in the burnout oven.
Burnout cycle for diamonds and emeralds max. burnout temperature = 630°Ctime 6h metal casting temperature = 480°C-530°C for cubic zirconia, rubies, sapphires, garnets and synthetic stones max. burnout temperature = 680°Ctime 5 h metal casting temperature = 550°C-600°C
Suitable alloys and casting
Alloys containing de-oxidising agents and with low shrinkage rates are the most suitable. Stone casting with invisible setting can be implemented with silver, yellow-, pink- and white gold in all karats.
Melting and casting method
Melting can be effected with the centrifuge system or with suction/pressure. If melting with palladium white gold it is advisable to use a centrifuge with vacuum and to accurately measure the temperature of the metal. A good melting plant will give a better and, above all, a more constant product quality.
After melting, flasks must be allowed to cool gradually to prevent thermal shock which could ruin the stones.
Flask cooling time:
only diamonds 20 minutes
all other stones 60 -120 minutes
Finishing of cast pieces
Cast pieces may be finished with traditional methods by hand or with automated systems, as long as the compounds and added products are suitable for the hardness of the stones.
Casting tree in gold with invisible setting and some finished rings and bracelet
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