I agree with Bill (whatwoodido). There's so much confusion about mahogany, that one major seller lists sapele as the same as African Mahogany. There's a good little blerb about them all here:
http://www.hobbithouseinc.com/personal/woodpics/mahogany,%20african.htm
I can't remember hobbithouseinc's name, but he knows a lot more about wood than I do. Many use his site for wood identification, including me. He says that African Mahogany is a true mahogany, but others say that it isn't. The debate goes on. I just know that I like it for furniture, but it is rather plain for pens, if it isn't figured in some way. Yours looks like it may be ribbon striped, which is best for pens, if it is cross-cut, or bias-cut.
Sapele is said by most to be "mahogany-like". As African Manogany does look so similar to Sapele, it would be tough to distinguish between the two, unless you take a magnified pic of the end grain. Most of the top wood identifiers use end grain to ID wood. The other views may look identical, but end grain will differentiate the two. Now, you just need that magnified shot and a way to determine which parenchima (sp?)and so forth constitutes the difference. I have to look at my book and it doesn't list all species. Good luck.
Rob