This is three coats of each, except the Milani, which lived up to the "One Coat Glitter" tag line on the bottle. We obviously have two pairs here: Atlantis and Henley Regatta are very much on the green side of blue green and the other two are clearly blue. Despite my concerns when I first swatched it, Henley Regatta can be worn alone, as can Atlantis and Blue Flash. I think Sexy Siren needs "underwear" or maybe just a fourth coat.
Looking at Atlantis and Henley Regatta a little closer, the former has sparser and larger glitter with scattered sparks of holo as well as a more pigmented base. Both are great, but they're not interchangeable.
To finish up this swatching session, I swapped the two blues for blue greens that looked more like Atlantis in the bottle, Nicole by OPI Nicole ... Spotted (why an ellipse in the middle of the name, OPI? Why?) and Sinful Nail Junkie.
Oh my, we've got some sheerness going on with those last two, don't we? And the expensive brand is more sheer than the cheapie (each are three coats). They're pretty, but I'm not sold on visible nail line with colors like this so I'll be layering them. Fortunately, I love layering.