tChess is a "universal binary" that runs equally well on the iPhone and the iPad.
Unlike several other chess games, you can buy one copy of tChess and use it on all of your devices.
When the iPad was released, several new graphical options were added to tChess to take advantage of the larger screen.
One option is a 2-D chess set with realistic
pieces that were created by raytracing 3-D models.
The other option is a realistic 3-D chess set that can be rotated and zoomed with multitouch gestures.
Both options are available in wood and marble. (Marble requires tChess Pro.)