To achieve the colour of red tigers eye the more familiar brown and yellow stone is heated. Black tigers eye is produced in the same way.
Whilst red tigers eye loses any chatoyance that may be present after having been heated, in the black stone it can still be seen. I believe this is because of the temperature used to bring about the change in colour.
Heat treatments have been used for thousands of years to enhance or change the colour of minerals and gemstones. Ancient Greek philosopher Theophrastus wrote in depth about the effects of heat on stones.
This red tigers eye stone makes a beautiful pendant. It has been slightly reduced because of an imperfection on the back.