Genuine reclaimed tiles can vary considerably in colour, and exact size. You should discuss this with your installer / builder / designer to ensure they are working with a product of this nature and this it is suitable for your project.
Brick, approx. 12cm x 25cm x 2.5cm, Hexagon, approx. 15cm x 15cm x 2.0cm, Rectangle, approx. 16cm x 30cm x 2.0cm, Square, approx. 16cm x 16cm x 2.0cm