Precision Metalsmiths (PMI) has announced that it has been awarded a new patent for investment casting for platinum jewellery.

The Cleveland-based company said the patent was awarded to a totally new, solid mould investment, specifically developed for investment casting platinum jewellery.

The new mould investment is also reportedly suitable for other applications, and for other high melting alloys such as cobalt chromium, nickel chromium and steels including stainless.

Compared to magnesium phosphate jewellery investments of the older type or the more recent dental adaptations, the new investment provides superior finishes, while still providing the capability to be invested and cast the same day, PMI claims.

The new investment is covered by US Patent 6,746,528, recently issued to Robert A Horton and Claude H Watts, and assigned to PMI.

The substance provides the great advantage of being used with water and no acid or other liquid are required and can be mostly removed by quenching the hot mould in water, as is done with gold investments. These advantages over the phosphoric acid investments are achieved with no loss in quality.

An investment casting is a near net shape made by the "lost wax" process that features cast-in-detail, tight tolerances, and excellent surface finish.