Natural Rough Bicolor Tourmaline · 1.64 ct · For Faceting · Unheated

This natural Bicolor Tourmaline rough weighs 1.640 carats and displays a distinctive natural transition between two contrasting colour zones. One side shows a subtle greyish-greenish white appearance, while the opposite portion develops into a deep to bright green, creating a clearly individual bicolour crystal.

Measuring approximately 18.0 × 4.2 × 2.0 mm, the specimen has a strongly elongated and slender natural form. Its unusual proportions offer interesting possibilities for elongated faceted designs, custom lapidary work, rough gemstone jewellery or collection purposes.

The material is transparent, allowing the internal colour distribution and structural characteristics to be examined before cutting. The transition from the pale greyish-greenish white zone into the stronger green section is one of the principal visual features of the rough and should be considered carefully when determining the cutting orientation.

In bicolour Tourmaline, colour zoning develops naturally during crystal growth as changes in chemical composition occur within the growing crystal. This can create distinct colour sections within a single piece of Tourmaline rather than representing a surface effect or treatment.

The deeper green portion provides strong colour concentration, while the lighter section creates visual contrast and emphasises the natural zoning of the specimen. Depending on orientation and final design, a cutter may choose to preserve both colour zones within one faceted gemstone or use the rough in a way that concentrates one particular colour region.

Natural inclusions, internal growth features and minor fissures may be present within the transparent material and should be considered during preforming. The relatively shallow 2.0 mm depth is particularly important for yield planning, as excessive removal of material may substantially reduce the finished weight.

The external surfaces remain naturally irregular and unpolished. Luster is therefore not formally graded in the rough state, although Tourmaline typically develops an attractive vitreous luster after successful faceting and polishing.

Gemstone Details

Gemstone: Natural Tourmaline
Colour Type: Bicolor Tourmaline
Carat Weight: 1.640 ct
Measurements: 18.0 × 4.2 × 2.0 mm
Form: Natural Rough
Colour: Greyish-Greenish White transitioning to Deep / Bright Green
Colour Classification: Multicolor / Bicolor
Transparency: Transparent
Luster: Not Graded in Rough State
Treatment: Not Specified
Potential Use: Faceting / Lapidary Work / Rough Gemstone Jewellery / Collection

This 1.640 ct natural Bicolor Tourmaline rough is distinguished by its transparent body, pronounced elongated form and attractive transition from a pale greyish-greenish white zone into deep to bright green. Its natural colour zoning offers particularly interesting design possibilities, while the slender dimensions require careful orientation and yield planning during faceting.