Not a diamond; this is a piece of cobalt blue colored glass or slag glass, exhibiting characteristic conchoidal fracture patterns.
Not a diamond; this is a piece of cobalt blue colored glass or slag glass, exhibiting characteristic conchoidal fracture patterns. · Raw, unpolished, irregularly shaped rough fragment (not a standard faceted diamond cut).
Not applicable (Rough, unworked material with natural fracture faces). Cut
Carat
Cannot be precisely determined without physical scale measurements, but estimated to be a large chunk (potentially 50+ carats equivalent if dense).
Color
Vivid Cobalt Blue (Fancy Dark Blue in gemological terms, though not a diamond color grade).
Clarity
Not applicable to glass, but visually translucent with internal flow lines and bubbles typical of glass.
Shape
Raw, unpolished, irregularly shaped rough fragment (not a standard faceted diamond cut).
Overall Assessment
The specimen in the image is definitively not a diamond or any precious gemstone. It is a piece of cobalt blue glass displaying prominent conchoidal fractures and internal flow structures, common in industrial slag or decorative glass fragments.
Cut Quality
Not applicable (Rough, unworked material with natural fracture faces).
Brilliance
Low to moderate vitreous luster, lacks the high refractive index and dispersion of a diamond.
Fire
Minimal to none; glass has a much lower dispersion rate than diamond.
Scintillation
Poor, as the material is not faceted to reflect and return light.
Proportions
Irregular rough proportions; no table, depth, crown, or pavilion angles apply.
Symmetry
Asymmetrical due to random fracture surfaces.
Polish
Unpolished, rough fracture surface showing conchoidal ripples.
Fluorescence
Unknown without UV testing, though cobalt glass often shows no or weak fluorescence.
Inclusions
Internal gas bubbles and flow lines, which are definitive indicators of manufactured glass rather than a natural gemstone or diamond.
Blemishes
Surface conchoidal fractures, chips, and uneven texture.
Origin
Man-made glass (industrial cullet, slag glass, or decorative glass).
Treatment Detection
Man-made colored glass; colored using cobalt oxide additives.
Estimated Value
Nominal decorative or craft value (typically less than $10), as it is industrial or decorative glass.
Certification Estimate
Not eligible for gemological certification by major labs like GIA or AGS as it is not a genuine gemstone.
Investment Potential
None; glass holds no investment or resale value as a gemstone.
Similar Diamonds
None, as this is completely unrelated to diamond or corundum (sapphire).
Setting Suggestions
Not suitable for fine jewelry settings due to softness (glass is around 5.5 on the Mohs scale).
Care & Maintenance
Handle with care to avoid chipping; clean with mild soapy water and a soft cloth.
Interesting Facts
Cobalt blue glass has historically been used in decorative objects, bottles, and as cullet glass, often mistaken by novices for rough blue sapphire or rare diamond material due to its striking color.