Gemstone Encyclopedia

Fire Opal vs. Mexican Fire Opal: What the Trade Name Really Means

Fire Opal vs. Mexican Fire Opal: What the Trade...

Understand the gemological distinction between fire opal and fire-colored precious opal, why the term is confusing, and how to tell them apart.

Fire Opal vs. Mexican Fire Opal: What the Trade...

Understand the gemological distinction between fire opal and fire-colored precious opal, why the term is confusing, and how to tell them apart.

Seeing Dumortierite: How Refraction Reveals Its Identity and Optical Character

Seeing Dumortierite: How Refraction Reveals Its...

Explore how dumortierite's biaxial optics, refractive index, birefringence, and pleochroism distinguish it from other blue gem materials.

Seeing Dumortierite: How Refraction Reveals Its...

Explore how dumortierite's biaxial optics, refractive index, birefringence, and pleochroism distinguish it from other blue gem materials.

How Light Source Changes the Look of Chalcedony: Color Change, Play of Color, and Optical Effects Explained

How Light Source Changes the Look of Chalcedony...

Learn why chalcedony cannot display true color change or play of color, how its microcrystalline structure affects light, and how laboratory growth clarifies gemological identification.

How Light Source Changes the Look of Chalcedony...

Learn why chalcedony cannot display true color change or play of color, how its microcrystalline structure affects light, and how laboratory growth clarifies gemological identification.

Why Dioptase Breaks So Easily: Hardness, Cleavage, and the Copper Silicate Family

Why Dioptase Breaks So Easily: Hardness, Cleava...

Dioptase is a beautiful copper silicate that cleaves easily. Discover why its Mohs hardness of 5 does not reflect its extreme fragility, and how its crystal structure controls its behavior.

Why Dioptase Breaks So Easily: Hardness, Cleava...

Dioptase is a beautiful copper silicate that cleaves easily. Discover why its Mohs hardness of 5 does not reflect its extreme fragility, and how its crystal structure controls its behavior.

Rubellite Hardness and Toughness: Why Orientation and Structure Matter

Rubellite Hardness and Toughness: Why Orientati...

Discover why rubellite tourmaline is hard yet brittle, how cleavage and internal strain affect durability, and how these properties compare with other gemstones.

Rubellite Hardness and Toughness: Why Orientati...

Discover why rubellite tourmaline is hard yet brittle, how cleavage and internal strain affect durability, and how these properties compare with other gemstones.

Why Star Ruby Requires a Cabochon Cut

Why Star Ruby Requires a Cabochon Cut

Discover why star ruby is cut as a cabochon: the science of asterism, orientation of rutile needles, and why faceting destroys the star.

Why Star Ruby Requires a Cabochon Cut

Discover why star ruby is cut as a cabochon: the science of asterism, orientation of rutile needles, and why faceting destroys the star.