Iolite’s strong pleochroism makes the gem tricky to cut for best color. This in turn continues to pose challenges to producers and buyers interested in promoting the attractive yet problematic gem to retailers as an affordable blue-gem alternative.

Iolite falls at 7 to 7.5 on the Mohs hardness scale, but given that it has distinct cleavage in one direction, its toughness is only fair. This makes iolite vulnerable to breakage when set in a ring or other setting exposed to rough daily wear.

Unlike tanzanite, iolite is rarely treated. Fine iolite comes by its beautiful blues and violets naturally. Its freedom from enhancement other than normal cutting and polishing is a selling point when customers consider that most blue gems, from inexpensive blue topaz to fine sapphire, receive routine treatment of one type or another.