Sorry it took so long to get back to you about the marmalade. I just now am looking back at many of the pictures I have looked at. See this page for some recipes. I am not a cook but I looked this up.

http://kumquatgrowers.com/recipes.html

Thank you for that info Dud - I was wondering if I could make a marmalade with this bitter variety.

Alandra - I did no editing with this one - I was rather surprised how the light grabbed it too - it almost looked metallic to me - but it isn't!

Good picture. There are at least two different varieties of kumquats. One is sweet. The other is bitter. My friend has two trees next to each other of different varieties.