Erma Boécourt SA

Swiss precision, quality and expertise

Machining techniques

Erma Boécourt SA uses sapphire produced using the Verneuil and Kyropoulos processes.

The Verneuil process

The Verneuil process

The Verneuil process produces sapphire boules, also known as stalagmites. The technique uses flame fusion to melt pure aluminium oxide at a very high temperature (around 2000 C°). This creates drops that fall onto a seed crystal, which in turn becomes a sapphire boule (crystal).

Using this method, it can take from several hours to several days to grow a sapphire boule. A crystal is formed by superimposing layer upon layer of melted material. 

The Kyropoulos process

The Kyropoulos process involves completely melting the raw material so that a single crystal can be grown by directional solidification. The seed grows from the melt as the temperature cools. This makes it possible to grow larger-diameter sapphire ingots for producing larger ébauches to meet the needs of our customers.

Kyropoulos process