Royal Blue Obsidian Identification Guide

What Royal Blue Obsidian Looks Like

Royal blue obsidian is a volcanic glass (amorphous silica-rich rock) that displays a blue to blue-violet appearance. Note: most "royal blue obsidian" on the market is actually colored/manufactured glass, because natural pure-blue obsidian is very rare. Natural blue tones in true obsidian usually appear as a sheen from microscopic inclusions rather than a deep transparent body color.

• Color: Deep blue to blue-violet; natural pieces often show a blue sheen over a darker base.
• Luster: Bright vitreous (glassy).
• Transparency: Translucent to transparent on edges.
• Habit: No crystals — massive glass with smooth, rounded forms and razor-sharp conchoidal fracture edges.

Step-by-Step Field-ID Checklist

1. Look for conchoidal fracture. Curved, shell-like breakage with sharp edges is the signature of all obsidian and glass.
2. Check for crystals or grains. There are none — obsidian is fully glassy. Any visible crystal grains rule it out.
3. Inspect for bubbles. Manufactured glass often has perfectly round trapped air bubbles; natural obsidian rarely does (it shows stretched/elongated micro-bubbles instead).
4. Test hardness — scratches glass at the low end (Mohs ~5-5.5).
5. Judge the color source — a uniform see-through royal blue strongly suggests manufactured glass.

Key Diagnostic Tests

• Mohs hardness: 5-5.5 (softer than quartz; a steel file scratches it).
• Streak: White.
• Cleavage: None; conchoidal fracture.
• Density: ~2.35-2.6 g/cm3 — light, similar to bottle glass.
• Warmth: Glass feels slightly warmer to the touch than dense crystalline gems.
• Acid: Inert.

Common Look-Alikes and How to Tell Them Apart

• Manufactured/dyed glass ("slag glass"): The most common substitute; tell-tale perfectly spherical bubbles, overly uniform color, and sometimes mold seams. Natural obsidian lacks seams and round bubbles.
• Blue goldstone: Glass with embedded copper sparkles — has glittering flecks obsidian lacks.
• Other sheen obsidians (rainbow, blue sheen): Same material; the color is an iridescent layer, not body color — tilt to see the sheen move.
• Blue chalcedony/agate: Harder (Mohs 7), waxy luster, no glassy conchoidal sheen.

Where It Is Found

Natural obsidian forms at rhyolitic lava flows worldwide — Mexico, the western USA (Oregon, California, Idaho), Iceland, and Armenia. Genuinely blue natural obsidian (usually as a sheen) is scarce; buyers should be skeptical of vivid transparent blue pieces.

Field Tips and Common Mistakes

When evaluating a "royal blue obsidian" piece, the most telling test is to backlight it with a strong flashlight and study the interior with a loupe. Natural volcanic glass commonly shows faint flow banding, stretched teardrop micro-bubbles, and tiny crystallites; manufactured glass tends to be optically clean except for perfectly round bubbles and may reveal mold seams or a slightly oily swirl pattern. A uniform, saturated transparent blue is the strongest warning sign of man-made glass.

A frequent misconception is that all blue sheen on dark obsidian indicates the rare "blue obsidian." In genuine sheen material the blue is a surface-play iridescence from nanoscale inclusions that shifts and disappears as you tilt the stone, whereas a fixed body color that looks the same from every angle points to dyed or melted glass. Combine the tilt test with the Mohs 5-5.5 hardness check before trusting any blue obsidian claim.