Imperial Topaz | Gemopedia

At the height of Imperial Russia's power, orange-pink topaz was brought from Brazil to decorate the jewelry of the Tzarina. Since then, these colors have been known as imperial topaz, and still today remains one of the most coveted topaz varieties. Interestingly enough, some sources dispute this legend and state that imperial topaz was indeed named in honor of the Brazilian ruler in power at the time, Emperor Don Pedro. Classified as a rare collector's gem, the world's supply of imperial topaz comes from sources in the Brazilian state of Minas Gerais. It is generally the reddish-orange or orange-red variety of topaz that's considered "imperial." Some also consider yellowish-orange, cognac-colored and pure orange to be imperial topaz.
Colors
Fine Medium Reddish Orange, Orange Red

Imperial Topaz Classification

Common Name

Imperial Topaz

Species

Topaz

Variety

Imperial Topaz

Colors

Fine Medium Reddish Orange, Orange Red

Alternate Names

Gemstone Groups

Key Separations

refractive index, birefringence, optic character; possibly specific gravity.

Comments

Biaxial positive common point is 0.001 from low RITopaz can have an RI of 1.619 to 1.627 (+0.010/-0.010).

Imperial Topaz Optical Properties

Transparency

Transparent

Refractive Index

1.629-1.637

Birefringence

0.008-0.01

Optic Character

Biaxial

Optic Sign

Positive

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: inert to weak greenish white
LWUV: inert to moderate orange or yellow

CCF Reaction

Pleochroism

Dichroic, weak to moderate light red and orangy red to yellow

Dispersion

Strength: weak fire Value: 0.014

Comments

Imperial Topaz Chemistry & Crystallography

Chemical Name

aluminium silicate fluoride hydroxide

Chemical Formula

Al2(F,OH)2SiO4

Synthesis

Crystal System

Orthorhombic

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline

Comments

Imperial Topaz Characteristic Physical Properties

Hardness

8

Streak

White

Specific Gravity

3.49-3.57 Typical:3.53

Toughness

Good

Inclusions

Imperial topaz is a type II clarity stone. Stones sometimes contain long tube-like cavities containing liquid, healed fractures and areas that look like they are starting to cleave. Stones might include 2-phase and 3-phase inclusions some of which contain more than one liquid that have not been mixed.

Luster

Vitreous

Stability

Fair

Fracture

Conchoidal

Cleavage

Perfect, in one direction

Comments

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