Nhra_20 is right, the Green Pages link (on the left in the blue area) is a great resource to find places that sell daylilies. Once you are in the green pages just click on the blue Daylilies at the top.
There are 3 daylilies registered with Diamonds in the Sky in their names, I'm not certain which one you are looking for.
Diamonds in the Sky (Peat 2000), the image below was posted to the NGA database from Crossview Garden. This is a link to their website
http://www.crossviewgardens.co...
Westfield Diamonds in the Sky (Sheilds 2005), we have no images entered for this one in the NGA database. Here is a link to the AHS registration page which shows an image. I do not know who offers it for purchase.
Jammin's Diamond's in the Sky (Singletary 2012), this image is posted to the NGA database from the hybridizers website where it is available. Here's the link to the page on their website
http://www.jamminsdaylilygarde...