I love the transformation it made going from dime store glass to opaline in a matter of minutes.
When I selected my glassware, I looked for inexpensive pressed glass that had similar characteristics in their design. So even though the patterns differ, each one had a diamond motif that helped tie them together.
To make these, I thoroughly cleaned my pieces in soap and water then wiped them down with isopropyl alcohol to remove any greasy residue. Next, I simply sprayed the outside of the glass with several light coats of paint (Rust-oleum's "Blue Sky") while leaving the interior unpainted. This creates the dimensional look of opaline and keeps the interior scratch-free.
Keep in mind that spray painted glassware is fragile. I only use it on decorative items or ones that will get minimal use. However, if you'd like to try it on an item that may get more wear, one kind commenter recommends this sealer by Krylon to help protect the finish.