A polished black granite slip under.

This can be used to create a tongue behind a hearth and can make for a neater finish.
A tongue can also be created by cutting the hearth when fitting, but it is not advisible to run the hearth to far under the grate as it will simply crack due to heat from the fire. The usual method is to concrete under the grate and spray it black.

Approximate size - 30" x 6"