3 things you need to make an object
Mesh
Texture Image
Material File & Code
So, you have the image, now you need to make the material file. Find the crystal material file, and make a copy of it. Rename the copy if you want. Now open it in notepad. Change the CrystalMat to whatever you want, and then in the image spot, put the name and format of the image you're going to use.
Depending on if you used a PNG or JPG, you would put
CrystalTex2.jpg
or
CrystalTex2.png