Black star diopside 2.47ct 9x7mm oval cabochon

An oval black cabochon with a four-ray star where the arms appear broad and silky in character, spreading softly from the center rather than forming sharply defined lines. The star is fully visible across the dome and the golden-bronze rays carry a gentle, diffuse quality. The stone is opaque with a deep black body color and a well-polished surface.

The phenomenon at work here is asterism, in which a direct light source interacts with fine, parallel needle inclusions within a gem to produce a bright, moving ray across the surface of a polished dome. Black diopside from Africa forms its four-ray cross from two sets of crossing rutile needles within the crystal structure, and the breadth or softness of those arms reflects how those inclusions are distributed in each particular stone. The stone is untreated.

• Stone type: Natural diopside
• Weight: 2.47 ct
• Size: 9x7 mm
• Color: Black
• Phenomenon: Asterism (4-ray star)
• Cut: Oval cabochon
• Clarity: Opaque
• Treatment: Untreated
• Origin: Africa
• Hardness: 5.5-6 (Mohs)

Natural black star diopside, untreated, asterism, sold loose.