If you are just butting the wood to the marble, typically you would do it so that when the door is closed you see only one flooring from each side. In my house, the bathrooms have a marble threshold between the wood floors and the tile and it is the entire width of the jamb. Is your threshold going to be inserted into the floor or does it sit on top of the flooring? How wide is it?

I would probably center the threshold directly under the door, unless that puts it past the jamb on one side.

Hi Linda,

Thanks for your feedback. The marble is about 1/4 inch higher than the wood. i'm thinking that the marble and wood should meet directly under the door when it's closed. the door will be mostly opened :) and the 'step up' will be in the middle of the jam which I'm concerned will look strange.

forgot to add it's a 3/12 X 30 inch marble threshold

Does it have a bevel on one or both sides? If so, it will probably look ok. Lay it down and take a look

What did you do @siobhanblake? Can you post a picture (almost 10 years later :) )