Without looking at the filenames, can you tell the difference? (Apart from having a third hand to take the black shots and myself to take the blue?)
I did them both the same way - base coat, two coats of the base color (and dried completely), shatter/crackle, top coat. I polished in the same direction on each nail (for both colors - middle fingers horizontal, ring and thumbs vertical, baby and index in opposite diagonals) and you can tell with both polishes by the way they crack how I did it.
The black is OPI, and the blue is China Glaze.
I found the OPI to be a bit more user friendly - you can see that it generally shattered fairly consistently, and it goes on like regular polish. China Glaze was a bit thicker, sort of tarry, and to thin it out (check my left middle finger) it just gets worse. By the end of my right hand I think it looked comparable, and pretty cool, but it's not quite as fool proof. Also, on my left thumb and index finger - where's the effect? And on my ring finger, how come there are slits on the end and crackling toward the cuticle? Then my right thumb completely separated and it looks like I missed a spot, but on the right index it didn't crackle very well. The last three fingers on my right hand look pretty good, so I'm not sure what gives. Maybe I'll do a "take two" to see if practice will improve. ;)
Overall - both worth it. China Glaze is much easier to find (Sally's has it, OPI is only available in salons) and I think retails for slightly less... They offer very different color selections too, so buy what you like and work it!
MK Base,
OPI Simply Smash-ing, Black Shatter,
Love & Beauty Fuchsia,
China Glaze Crushed Candy Crackle,
Beauty Secrets Top Coat.