To the untrained eye these gemstones can look fake – rather like someone has sneakily cut & glued two gemstones together.
However, bi-coloured gemstones are one of nature’s gemmological delights.
We have some zesty blue-green-yellow sapphires at Holts Lapidary (above) and Ametrine, a bi-coloured gemstone which is a mixture Citrine and Amethyst (below).
Bi-coloured gemstones are usually formed when the trace elements that give the gemstone it’s colour change in concentration or composition during the crystal’s growth. This causes colour zones across the length of the crystal or through it’s core.
Why have one colour when you can have two?
Bi-colour crystals require a skilled lapidary to carefully assess the colour zoning within the crystal in order to cut and facet the gemstone so that the colours are best displayed to the desired effect.