Assertion: alexandrite's color change | /r/HasProperty | gübelin
Facets:
Source sentences:
text: A similar color change is also observed for other varieties of gem minerals such as garnet, sapphire, spinel, kyanite, fluorite, and diaspore (Bosshart et al., 1982; Gübelin and Schmetzer, 1982; Schmetzer et al., 2009).