- Alexandrite and other colour-change gemstones
- Amber and Copal
- Corundum – lattice diffusion of foreign elements other than hydrogen
- Corundum – No indications of heating and Indications of heating
- Corundum – residues from the heating process in healed fissures
- Corundum with glass filled fissures modifying the clarity
- Emerald – fissure filling clarity enhancement
- Gemstones – Colour authenticity is undetermined
- Hydrophane Opal
- Jade and Related Minerals
- Organic Fillers in Gemstones
- Padparadscha sapphire
- Paraiba Tourmaline
- Pearl
- +44 (0)207 491 4777
- contact@gcslab.co.uk
- 30 New Bond Street, London W1S 2RN
GCS - Gemmological Certification Services