In the GIA colour-grading system for coloured gemstones, bV denotes a bluish violet hue — that is, a stone whose dominant hue is violet, modified by a secondary component of blue. The notation follows GIA's consistent convention: the modifying hue is written first, in lower case, and the dominant hue second, in upper case. A stone graded bV is therefore primarily violet, with blue playing a subordinate but perceptible role in its overall appearance.

The GIA Hue-Code Framework

GIA's standardised hue codes were developed as part of its coloured-stone grading methodology to replace the imprecise trade vocabulary — "cornflower blue", "periwinkle", "indigo" — that had long made precise colour communication unreliable between laboratories, dealers, and buyers. In this system the visible spectrum and its intermediary hues are divided into a defined set of principal hues (red, orange, yellow, green, blue, violet, and purple), each assigned a capital-letter abbreviation. When a stone's colour falls between two principal hues, a modifier prefix in lower case is added: hence bV for bluish violet, vB for violetish blue, pV for purplish violet, and so forth.

The distinction between bV and its near neighbours matters considerably in commerce. A stone graded vB (violetish blue) is fundamentally a blue stone with violet inflection; a stone graded bV is fundamentally violet with blue inflection. Though the perceptual difference can be subtle under certain lighting conditions, the two designations place a stone in different market categories, with different reference comparators and, frequently, different valuations.

Gemstones Commonly Graded bV

Several important gem species regularly produce colours that fall within the bluish violet range:

• Tanzanite — The most commercially prominent bV gem. Fine tanzanite from the Merelani Hills of Tanzania often displays a rich violet hue with a distinctly blue modifier, and the interplay between these two hues — shifting with lighting angle and light source — is central to the variety's appeal. Stones that lean toward bV rather than vB or pure violet are frequently considered the most desirable by the international trade.
• Sapphire — Violet sapphires from Sri Lanka, Madagascar, and other localities can exhibit bV colours, particularly in lighter to medium tones. Such stones occupy a position between the classic blue sapphire market and the violet-to-purple sapphire niche, and their grading as bV rather than vB can influence whether they are traded primarily as sapphires or as violet stones.
• Spinel — Certain spinels, particularly from Sri Lanka and Tanzania, produce bluish violet hues. These are distinct from the more commercially recognised cobalt-blue spinels and represent a quieter but genuinely attractive colour range within the species.

Practical Significance in Grading and Trade

When a gemmological laboratory such as GIA issues a coloured-stone report, the hue code appears as part of a three-component colour description alongside tone and saturation. The full colour designation for a fine tanzanite might read, for example, "medium dark, highly saturated, bluish violet" — with bV as the hue component. This precision allows a buyer or appraiser to reconstruct a reliable mental image of the stone's colour without having the stone in hand, and to compare it against other graded stones in a consistent framework.

For dealers working across multiple laboratories and grading systems, it is worth noting that not all organisations use GIA's exact hue-code notation. The American Gem Trade Association's GemSet colour reference and other proprietary systems employ related but not identical terminology. When a report specifies bV, it should be understood as GIA nomenclature specifically, and cross-referenced accordingly when comparing reports from different issuing bodies.