What is a Montana sapphire?
By Jared James · Last updated 21 May 2026
Definition
Montana sapphires are natural sapphires mined in the state of Montana, USA, primarily from the Yogo Gulch deposit and several alluvial sources along the Missouri River. They are valued for their unusual colour range, which includes steely blue-grey, teal, parti-coloured and pale green-blue tones that differ markedly from the deep blue of Kashmir or Ceylon sapphires. Yogo Gulch sapphires in particular are known for being naturally included in a vivid cornflower blue and are almost always unheated, which appeals to buyers who prioritise untreated stones.
Frequently asked questions
- What colours do Montana sapphires come in?
- Montana sapphires cover a broad range: steely blue, teal, blue-green, parti (showing more than one colour in the same stone) and pale pastel tones. Yogo Gulch stones tend to a cleaner cornflower blue. The teal and parti-colours are distinctive and have become very fashionable.
- Are Montana sapphires usually treated?
- Many Montana sapphires are sold untreated, particularly Yogo Gulch stones, which are valued precisely for their natural colour without heat enhancement. Some alluvial Montana sapphires are heated to improve colour and clarity, as is common practice across the sapphire trade.
- Are Montana sapphires expensive?
- Fine quality Montana sapphires, especially untreated Yogo Gulch stones in vivid blue, command strong prices. The parti and teal colours from alluvial sources can be more affordable but have grown in value as their popularity has increased.
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