Tasha at By Gum, By Golly has one of the best handmade buttonhole tutorials I’ve seen.
She includes a scan from a vintage sewing pattern that is large enough and clear enough to give you the exact stitching information you need.
There is also a good summary of the types of silk buttonhole twist available and some alternative threads that can be used.
Tasha’s photos are bright and clear. She uses a red thread for the buttonholes so you can easily see how the hand sewing should proceed.
You’ll be very glad you stopped by her blog to get this information. I’m very happy I can recommend this posting because it fills in the needed information on this topic over here.