Assertion: opal | /r/HasProperty | impregnated with colorless oil
Facets:
Source sentences:
text: Some opals are also impregnated with colorless oil, wax, resin, plastic, and hardeners to hide crazing or improve durability.
text: Opal is a soft stone and therefor is occasionally treated or impregnated with colorless oils, plastic, resin or wax which act as a bonding agent, reduce the visibility of the inclusions and improve the overall clarity of the stones.
text: Some opals are also impregnated with colorless oil, wax, resin, plastic, and hardeners to hide crazing or improve durability.