I applied Fault Line over Silver Dazzle, a Milani One Coat Glitter shade. The directions say to apply a coat of Crackle Glaze over a base color that is completely dry, allow the Glaze to dry 3-5 minutes, and then seal with a top coat. That's exactly what I did, but the finish looks a little "rough", especially on my index finger. I imagine that you'll get different degrees of satisfaction from the finish, depending on how the Crackle Glaze reacts over your base color.
The actual cracking pattern wasn't as dramatic as I'd hoped for, but again, I do think some experimentation is in order before I can truly say that I love this product. I certainly don't dislike it--the hours of entertainment it's going to provide me with are going to be endless! In my mind, I'm sure it's being compared to OPI Black Shatter, which gives a more shattered look that a crackle look. The veins are more refined, defined and more widely scattered on the OPI product, no matter what base finish I've used it on. The OPI product also begins its transformation very quickly, while the China Glaze product takes a minute or two longer to reach its final appearance.
Odds are that my lack of perfection in the application and finish is based more on the fact that I need to work with this polish more and try to find just the right amount to put on the brush. It is a little on the thick side, but all of the crackle-type polishes I've used are also this way. I ordered my set from Victoria Nail Supply and they arrived in just two days. They're priced at $3.10 each on their site.