treated gemstones according to CIBJO Blue Book
Baltic amber, like diamonds, coloured gemstones, corals or pearls may have been subjected to special treatments. Usually to change their colour, durability, stability and/or clarity.
The oldest records about improving the colour and transparency of gemstones are dated back nearly 4,000 years.
In ancient Rome, amber was also treated, if only to change its colour to a darker one and improve its clarity. For this purpose, slow cooking in fat of young goats was used and sometimes it was also dyed in different colours.
What happend with amber during treatment?
During heat and heat/pressure treatment of Baltic amber chemical processes occured:
- Oxidation process
- Loss of volatile compounds
- Saturation of multiple chemical bonds
Baltic amber colours can be changed in autoclave.
We can receive a wide range of colours:
- light yellow (lemon)
- orange (cognac)
- dark red (cherry)
The darker colours received during heating are only on the surface of amber. The colour change does not penetrate deep inside the stone. Thanks to the further processing, interesting colour transitions of tones can be obtained.
Visual effect of heat treatment and internal stress round fractures. ‘Sun spangles’ gained popularity in the 1970s to 1990s. Especially in Germany.
The green colour of Baltic amber is an optical effect. Very interesting and fascinating to look inside. It is made by light yellow treated amber with sun spangles painted or burned downside.