I have 21 front and 18 rear mammoths spokes...... Now with avon cobras.... (Long story about my vee rubber tires) I have regular spoke, the diamond is just how they cut the spokes, sort of an angular finish to them. Their a pain in the @ss to clean, but if have ZERO leaking issues so far, their true, and ride very nice..... I think DNA has some of the QA issues worked out now. Good wheels at a good price IMHO
I had a ride Wright twisted spoke wheel, diamond cut was an option and the above reply is right, it's just a way they make cuts in the spokes, the purpose of the cuts is to create a different angle for the sun to gleam off of.
I have the diamond spoke 21" and love them. Very nice in the sun going down the road. I don't think they are any harder to clean than other spoke wheels but I don't really let them get dirty either way.