Not a diamond; this is a piece of cobalt blue glass (often found as slag glass or cullet)
Not a diamond; this is a piece of cobalt blue glass (often found as slag glass or cullet) · Irregular raw chunk / rough fragment with conchoidal fractures
Not applicable (raw, uncut glass fragment) Cut
Carat
Not applicable for glass; heavy rough piece
Color
Deep Fancy Cobalt Blue
Clarity
Transparent with visible internal bubbles and flow lines characteristic of glass
Shape
Irregular raw chunk / rough fragment with conchoidal fractures
Overall Assessment
An interesting and vibrant piece of blue glass, but entirely lacking the physical, optical, and chemical properties of a diamond.
Cut Quality
Not applicable (raw, uncut glass fragment)
Brilliance
Low to moderate vitreous luster
Fire
None (glass lacks diamond dispersion)
Scintillation
Poor
Proportions
Not applicable
Symmetry
Asymmetric
Polish
Unpolished, natural fracture surfaces
Fluorescence
Inert to moderate under UV light
Inclusions
Gas bubbles, swirl marks, and flow lines visible internally
Blemishes
Surface chips and irregular texture
Origin
Man-made industrial glass or slag glass
Treatment Detection
Colored with cobalt oxide during manufacture
Estimated Value
Minimal (decorative or decorative mineral collecting value only, typically under $10)
Certification Estimate
Cannot be certified as a gemstone; laboratory testing (Raman spectroscopy or refractive index) would identify it immediately as glass
Investment Potential
None as a gemstone
Similar Diamonds
None, as it is completely unrelated to diamond
Setting Suggestions
Wire-wrapped pendant if desired for novelty wear
Care & Maintenance
Standard cleaning with mild soap and water; avoid hard impacts as glass is brittle
Interesting Facts
Cobalt blue glass is frequently mistaken by novices for rough sapphire or blue diamond due to its intense color