A DV fireplace is also known as a direct vent fireplace. For a small recap, a direct vent fireplace is a fireplace that has a sealed system that brings in air from outside then emits all waste back outside. Because a direct vent fireplace has a high heat output and is a sealed system, that requires a more heavy duty glass that can withstand a high heat output.
Ceramic glass is made to withstand a high temperature without shattering. This type of glass is most commonly used with a stove or fireplace that is sealed or closed off. This type of glass is used to withstand the heat of these types of fireplaces for the safety of owners.
The ceramic glass can withstand temperatures exceeding 1000°F. This allows the fire feature with the ceramic glass to withstand the heat output. Ceramic glass also is different when shattering, the glass does not shatter into tiny pieces like tempered glass but shatters in large pieces.