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Tourmaline

Tourmaline

Complex gem group with nearly every color including bicolor and multicolor crystals

Black Blue Green Multicolor Pink Red Yellow
Optical properties

Optical characteristics

Ref. index
1.603 – 1.644
Birefringence
0.014 – 0.041
Luster
Vitreous
Pleochroism
Strong
Fluorescence
Usually inert; some blue-green tourmaline may show weak LW response.
Origins

Source localities

Tanzania Tanzania: Merelani Hills
Notable

Tanzania produces chrome tourmaline (dravite) with strong green color from the Merelani and other deposits.

10% est. supply
Brazil Brazil: Minas Gerais / Paraíba / Bahia
Legendary ★ Top Source

Brazil is the primary global source of tourmaline, producing Paraíba, rubellite, indicolite, verdelite and watermelon tourmaline of exceptional quality.

40% est. supply
Afghanistan Afghanistan: Panjshir / Nuristan / Badakhshan
Premium ★ Top Source

Afghanistan produces fine pink, red and bicolor tourmalines from pegmatite deposits.

15% est. supply
Pakistan Pakistan: Shigar / Swat / Sapat Valley
Notable

Pakistan produces indicolite, pink and multicolor tourmalines from high-altitude pegmatites.

10% est. supply
Mozambique Mozambique: Montepuez / Alto Ligonha / Cuamba
Premium ★ Top Source

Mozambique produces copper-bearing Paraíba-type tourmaline and indicolite from the Alto Ligonha and Cuamba pegmatites.

15% est. supply
Nigeria Nigeria: Oyo / Ogun / Plateau fields
Notable ★ Top Source

Nigeria produces copper-bearing Paraíba-type tourmaline alongside Brazil and Mozambique.

10% est. supply
Treatments

Enhancement & treatment

Heat Heat Treatment, Tourmaline Heat treatment is used to improve tourmaline color and is often stable. Disclosure is… Color Enhancement Irradiation, Tourmaline Irradiation can alter tourmaline color centers. It may be used alone or followed by…
Inclusions

Inclusions & features

Crystals Crystal Inclusions Under 10x loupe: solid, well-formed mineral crystals trapped inside the host gem. They may… Fractures Feathers and Fractures Under 10x loupe: irregular internal surfaces that catch light and appear bright, wing-like, or… Fractures Fingerprint Inclusions Under 10x loupe: curved or wavy lines of tiny dots forming patterns that look… Needles Growth Tubes, Rain Inclusions Under 10x loupe: long thin hollow channels running parallel to each other and to… Multiphase Two-Phase Inclusions Under 10x loupe: a transparent irregular cavity containing both a liquid phase and a…
Identification

Instruments used

10x Loupe Your most-used instrument, start every examination here Polariscope Determines single vs. double refraction, quick and conclusive Refractometer Measures refractive index, the backbone of gem identification