Eric says: “This gem is a fine example of the rarer Yogo sapphire, mined at the Yogo Gulch and faceted many years ago; the blue is of medium strong saturation anf medium tone, evenly distributed through the gem, without any detracting secondary colours present. The clarity is eye-clean, as shown in the images.
Sapphires mined in Montana, USA, fall into two categories; the more common ones extracted from along the banks of the Missouri River which need heat treatment to reveal their bright colours, known as ‘Montana Sapphires’, and the rarer sapphires from the Yogo Gulch in Montana that need no heat treatment to reveal their vivid blue colour and are called ‘Yogo Sapphires’”.
0.99 carats, round brilliant cut, measuring 6.0mm diameter, 3.7mm in depth, not treated in any way.
Accompanied by an SSEF Gem Report 152031, 9 Feb 2026. See the scan stating “No indications of heating. Origin: Yogo, Montana (USA)”
Eric says: “This gem is a fine example of the rarer Yogo sapphire, mined at the Yogo Gulch and faceted many years ago; the blue is of medium strong saturation anf medium tone, evenly distributed through the gem, without any detracting secondary colours present. The clarity is eye-clean, as shown in the images.
Sapphires mined in Montana, USA, fall into two categories; the more common ones extracted from along the banks of the Missouri River which need heat treatment to reveal their bright colours, known as ‘Montana Sapphires’, and the rarer sapphires from the Yogo Gulch in Montana that need no heat treatment to reveal their vivid blue colour and are called ‘Yogo Sapphires’”.
0.99 carats, round brilliant cut, measuring 6.0mm diameter, 3.7mm in depth, not treated in any way.
Accompanied by an SSEF Gem Report 152031, 9 Feb 2026. See the scan stating “No indications of heating. Origin: Yogo, Montana (USA)”
Feel free to WhatsApp me to discuss this sapphire. I can video chat with you to show you the gem and/or book an appointment to see it in Hatton Garden at my place of work.
0.99 carats Yogo Montana sapphire
