My youngest daughter did just that. Hers came from The Tile Shop.

Just google porcelain tile that look like marble.

Here’s a shot during renovation

Here are a few Emser tiles that can be used on a shower floor:

• Reserva (several colors)
• Perspective Gray
• Marble Winter Frost (many sizes; mosaics can be used in showers)

I think those are marble though

Only the Marble Winter Frost is marble (my mistake). Reserva and Perspective are porcelain.

Porcelain that looks like marble is readily available. We used gloss 12 x 24 tiles in the tub/shower combo area and the same tile but honed for the floor.