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Amber

Last updated: April 2026

Fossilized tree resin; low density and organic inclusions distinguish it from glass and copal. Baltic amber fluoresces strong blue to bluish-white under LW UV. Dominican and Mexican amber show vivid sky-blue LW fluorescence. Burmese (Burmite) amber tends toward green or yellow fluorescence.

Amber has a specific gravity of 1.08 and a refractive index of 1.539–1.545, with a Mohs hardness of 2.0–2.5. It is singly refractive.

Physical & Optical Properties

RI Range1.539–1.545
SG Range1.05–1.09
SG Typical1.08
Hardness (Mohs)2–2.5
Crystal SystemAmorphous
Optic CharacterSR (Singly Refractive)
Fluorescence LWStrong blue
Fluorescence SWModerate Blue White
Chelsea FilterInert
PleochroismNone
ColorsYellow Orange, Brown, Red Pink, Green, Blue Violet
SpeciesOrganic
Yellow OrangeBrownRed PinkGreenBlue Violet

Measured with a polariscope, a refractometer, a hydrostatic balance, a Chelsea filter, a UV torch, a loupe, a darkfield loupe and a spectroscope — step-by-step for each.

Through the refractometer

Amber reads 1.542 1.40 1.45 1.50 1.55 1.60 1.65 1.70 1.75 1.80 REFRACTIVE INDEX DORotate the stone through a full 360°, watching the boundary. SEEOne boundary, at 1.542, and it does not move as you rotate. MEANSSingly refractive. A stationary single edge through thewhole rotation is the observation that says so. Computed from gems.json — edge positions are arithmetic, not drawn. RI increases upward; the field above the boundary is the dark one.

Drawn from the refractive index above, on a 1.40–1.81 scale. How to take this reading.

Through the polariscope

Amber Dark throughout (SR) 0° 45° 90° 135° ROTATION BETWEEN CROSSED POLARS Amber stays dark through the whole rotation. That is singly refractive: there is no second ray to rotate the plane of vibration back into the analyser. Computed from optic character and transparency in gems.json. A polariscope separates singly refractive, doubly refractive and aggregate — it does not show the optic sign.

Drawn from the optic character and transparency above. A polariscope separates singly refractive, doubly refractive and aggregate; the optic sign needs a conoscope. How to take this reading.

Specific gravity, and what it rules out

Amber SG 1.05–1.09 WHERE IT SITS, AND WHAT ELSE IS THERE 1.0 2.0 3.0 4.0 5.0 SPECIFIC GRAVITY Nothing else in the reference table shares this range. A careful hydrostatic reading here names Amber on its own. Amber is porous: it soaks up water during immersion, which raises the weight in water and makes the SG read HIGH. Heavy liquids damage porous material, so there is no clean fallback — treat any figure here as unreliable. Computed from the specific-gravity range in gems.json. Hydrostatic weighing — the bench method this site recommends; heavy liquids are toxic and regulated. Faint ticks are the other species in the table.

Drawn from the specific-gravity range above, against every other species in the table. How to take this reading.

Through the dichroscope

Amber One colour (no pleochroism) IDENTICAL AT EVERY ANGLE Amber shows no pleochroism, so both windows match at every orientation — turning the instrument changes nothing. That is a real negative result, and the reason it is worth knowing is below. Computed from pleochroism and pleochroic colours in gems.json. Window tints are derived mechanically from the colour words, not chosen; a neutral pair depicts no colour at all.

Drawn from the pleochroism above. Two windows that match mean either no pleochroism or the wrong angle — turn the instrument to tell. How the dichroscope compares.

CoralIvoryPearl

Key Differentiators

Treatments

Measurement Guides

How to Identify a GemstoneHow to Measure Specific GravityHow to Use a RefractometerUV Fluorescence Testing

Identifying an amber? Loupewise walks through these tests in order — RI, SG, fluorescence, and more.

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Studying for the GIA, FGA, or FEEG practical? Amber is one of the 132 species in Loupewise’s drill and exam pool — practice identifying it from its measured properties under timed exam conditions.

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