Liquid fingerprints in spinel are rather uncommon. Here we see a rare example, more highly magnified.

Natural Spinel  •  Not Determinable  •  Enhancements: None Detected (None)  •  Lighting Conditions: Dark Field
Photographer: Richard W. Hughes  •  Image Number: A-003-6222-2  • Field of View = 2mm

Gübelin, E.J. and Koivula, J.I. (2005) Photoatlas of Inclusions in Gemstones, Volume 2. Basel, Switzerland, Opinio Publishers, 830 pp.; RWHL*.

Liquid fingerprints in spinel are rather uncommon. Here we see a rare example.

Natural Spinel  •  Not Determinable  •  Enhancements: None Detected (None)  •  Lighting Conditions: Dark Field
Photographer: Richard W. Hughes  •  Image Number: A-003-6222-1  • Field of View = 7mm

Gübelin, E.J. and Koivula, J.I. (2005) Photoatlas of Inclusions in Gemstones, Volume 2. Basel, Switzerland, Opinio Publishers, 830 pp.; RWHL*.

A small tube-like cavity pierces the surface of this cobalt spinel.

Natural Spinel  •  Sri Lanka (Ceylon)  •  Enhancements: None Detected (None)  •  Lighting Conditions: Dark Field + Diffuse Fiber Optic
Photographer: E. Billie Hughes  •  Image Number: A-003-5162-1  • Field of View = 2mm

Gübelin, E.J. and Koivula, J.I. (2005) Photoatlas of Inclusions in Gemstones, Volume 2. Basel, Switzerland, Opinio Publishers, 830 pp.; RWHL*.

When we saw several metallic crystals in the interior of this spinel we became curious as to their identity. Micro Raman analysis revealed that they are graphite.

Natural Spinel  •  Afghanistan  •  Enhancements: None Detected (None)  •  Lighting Conditions: Dark Field + Diffuse Fiber Optic
Photographer: E. Billie Hughes  •  Image Number: A-003-5095-3  • Field of View = 2.5mm

Gübelin, E.J. and Koivula, J.I. (2005) Photoatlas of Inclusions in Gemstones, Volume 2. Basel, Switzerland, Opinio Publishers, 830 pp.; RWHL*.

These crystals, cut through on the surface of their spinel host, were identified with micro Raman as magnesite.

Natural Spinel  •  Afghanistan  •  Enhancements: None Detected (None)  •  Lighting Conditions: Dark Field + Overhead Fiber Optic
Photographer: E. Billie Hughes  •  Image Number: A-003-5095-2  • Field of View = 2.8mm

Gübelin, E.J. and Koivula, J.I. (2005) Photoatlas of Inclusions in Gemstones, Volume 2. Basel, Switzerland, Opinio Publishers, 830 pp.; RWHL*.

These crystals, cut through on the surface of their spinel host, were identified with micro Raman as magnesite.

Natural Spinel  •  Afghanistan  •  Enhancements: None Detected (None)  •  Lighting Conditions: Dark Field
Photographer: E. Billie Hughes  •  Image Number: A-003-5095-1  • Field of View = 2.8mm

Gübelin, E.J. and Koivula, J.I. (2005) Photoatlas of Inclusions in Gemstones, Volume 2. Basel, Switzerland, Opinio Publishers, 830 pp.; RWHL*.

A large mineral inclusion, identified with microraman as dolomite, stands out from its spinel host. Specimen courtesy Tristan Knowles.

Natural Spinel  •  Myanmar (Burma); Mogok/Namya  •  Enhancements: None Detected (None)  •  Lighting Conditions: Fiber Optic: Diffuse Oblique
Photographer: E. Billie Hughes  •  Image Number: A-003-4182-1  • Field of View = 6mm

This partially healed fissure in a fingerprint pattern consisting of interconnected tubes is a rare occurrence in natural spinel, and confirms that this Sri Lankan cobalt-blue spinel is natural. The form taken by the tubes reveals the isometric symmetry of the underlying spinel. In long-wave UV, this stone displayed a strong green glow, something that is also found in cobalt spinels from Vietnam.

Natural Spinel  •  Sri Lanka (Ceylon)  •  Enhancements: None Detected (None)  •  Lighting Conditions: Dark Field
Photographer: Richard W. Hughes  •  Image Number: A-003-4768-1

Gübelin, E.J. and Koivula, J.I. (2005) Photoatlas of Inclusions in Gemstones, Volume 2. Basel, Switzerland, Opinio Publishers, 830 pp.; RWHL*.

Hughes, E.B., Koivula, J.I., Manorotkul, W., Renfro, N. and Hughes, R.W. (2019) Spinel inclusions: An exercise in aesthetics. InColor, No. 43, pp. 48–55; RWHL*.

The strain pattern around this crystal in a spinel is evidence when observed between crossed polars.

Natural Spinel  •  Myanmar (Burma); Mogok/Namya  •  Enhancements: None Detected (None)  •  Lighting Conditions: Dark Field + Crossed Polars
Photographer: E. Billie Hughes  •  Image Number: A-003-4649-1  • Field of View = 4mm

Hughes, E.B., Koivula, J.I., Manorotkul, W., Renfro, N. and Hughes, R.W. (2019) Spinel inclusions: An exercise in aesthetics. InColor, No. 43, pp. 48–55.

This spinel contained a number of octahedron-shaped crystals filled with a transparent doubly refractive material, as well as hexagonal black plates of what is probably graphite. The doubly refractive nature of the filling becomes clear when the gem is viewed between crossed polars, as the inclusion lights up with interference colors against a black background. The ability of spinel to force its morphology on guest minerals has been dubbed “philoxenism” by John Koivula.

Natural Spinel  •  Not Determinable  •  Enhancements: None Detected (None)  •  Lighting Conditions: Diffuse Light Field + Crossed Polars
Photographer: Richard W. Hughes  •  Image Number: A-003-4131-2

Hughes, E.B., Koivula, J.I., Manorotkul, W., Renfro, N. and Hughes, R.W. (2019) Spinel inclusions: An exercise in aesthetics. InColor, No. 43, pp. 48–55.

Gübelin, E.J. and Koivula, J.I. (2005) Photoatlas of Inclusions in Gemstones, Volume 2. Basel, Switzerland, Opinio Publishers, 830 pp.; RWHL*.

This spinel contained a number of octahedron-shaped crystals filled with a transparent doubly refractive material, as well as hexagonal black plates of what is probably graphite. The ability of spinel to force its morphology on guest minerals has been dubbed “philoxenism” by John Koivula.

Natural Spinel  •  Not Determinable  •  Enhancements: None Detected (None)  •  Lighting Conditions: Diffuse Light Field (Transmitted Light)
Photographer: Richard W. Hughes  •  Image Number: A-003-4131-1

Hughes, E.B., Koivula, J.I., Manorotkul, W., Renfro, N. and Hughes, R.W. (2019) Spinel inclusions: An exercise in aesthetics. InColor, No. 43, pp. 48–55.

Gübelin, E.J. and Koivula, J.I. (2005) Photoatlas of Inclusions in Gemstones, Volume 2. Basel, Switzerland, Opinio Publishers, 830 pp.; RWHL*.

This crystal inside a spinel has displays striking parallel growth markings on its surface.

Natural Spinel  •  Myanmar (Burma); Mogok/Namya  •  Enhancements: None Detected (None)  •  Lighting Conditions: Dark Field + Diffuse Fiber Optic
Photographer: E. Billie Hughes  •  Image Number: A-003-3699-1

Gübelin, E.J. and Koivula, J.I. (2005) Photoatlas of Inclusions in Gemstones, Volume 2. Basel, Switzerland, Opinio Publishers, 830 pp.; RWHL*.