How much approximately does my loose diamond weigh in carats?

I have a loose marquise shaped diamond. Id like to buy a setting for it online but cant seem to figure out on my own what my carat weight is. What I do have are my dimensions! They are as follows:
It is 7 mm length, 4 mm width and when it lays on the side it is also 4 mm. Is anyone out there knowledgeable enough to give me a very close estimate on the carat weight? Its a beautiful diamond and I cant wait to get it set! Thanks in advance to anyone who answers!!!!!

this is a disaster waiting to happen, take it to a jeweler, ordering a setting online and not having it professionally sized is like buying a shoe for a kid you never met, it’s not gonna fit right.

Loose Diamond Beautiful
Loose Diamond Beautiful
Loose Diamond Beautiful