AHello pros, I would like to do the diamond shape design around a round cake but not sure how it is done. Also, how do you make all of the diamond shapes evenly around cake? Thanks in advance!!

How about using a cookie cutter? 

OR you could cut a paper pattern and mark the cake w/a toothpick.  Measure how wide you want the diamond shape and see if it will fit around the cake properly - adjust the pattern size to fit.

look up the jessica harris wax paper transfer technique as well

Are you talking about this style?

https://www.youtube.com/results?search_query=How+to+Create+a+Quilted+Pattern+on+a+Cake+

If so, you can also just buy a diamond impression mat.

ohhh I misunderstood what you were trying to do...sorry!

I just did one,  I took a tape measure ( one used for clothing to measure the around the pan size,  then I took the measurents of the diamond shape from side to side and took that number into the  # ( size around the pan )      example my 10 in round pan   32 in around,   my diamond shape was 3 inches wide.   so 10 around ( just shy of 11 )  here is a photo of the cake I recently did.  So I would have had two inches space   and I took the 11th diamond and placed it right in the middle of the last space and you couldnt tell it overlapped unless you looked really hard. , attached is the image of the one I did,  If that is what you meant by diamonds.