I decided to compare Vetro 058 Transparent Intense Dark Blue and Effetre 057 Transparent Intense Blue - even though the numbers are one different - they look the same.
And, in fact, the short answer is - they are the same. I can't find a difference. At all. Call 'em functionally the same.
The two rods in front, the one in the very front is the Effetre. The one behind is the Vetro.
Leftmost/Top - Vetro. Bottommost/Right - Effetre.
Vetro on the left, Effetre on the right.
Same thing, base of Vetro on the left, Effetre on the right. White dots - Effetre dots on the left, Vetro on the right.
That said - I think it is one of the most beautiful colours. Ever. I love this colour - this is the perfect transparent blue, as far as I'm concerned. Cobalt is generally too dark, Eff 054 Med Blue a little wishy-washy, and 056 not much better, and frequently, not much different. Hmm - maybe I need to blog that to prove the point.
This is an awesome rockin' color - feel free to buy the Eff or Vetro version - whichever is cheaper.