CiM Sacre Bleu (CiM555) is a gorgeous, vibrant, dark blue transparent. It's buttery to work, and its only real vulnerable spot is that it can be a little bit vulnerable to sooting if you work it too hot. It's interestingly reactive, it makes a nice base for silver glass, and just a beautiful colour of blue.
Here, you can see that although Sacre Bleu is essentially the same colour as Effetre Intense Blue, it's just a bit more saturated, working up darker. It's not quite as dark or as saturated as Effetre Cobalt, but its reactions are more similar to that colour.
Sacre Bleu does not change when it is reduced.
For some reason, silver leaf turned yellow and blue on top of Sacre Bleu. I looked back at previous test results, and this reaction is pretty consistent with what I saw when I tested Effetre Cobalt, so they must contain some similar ingredients.
The way silver glass develops colour on top of Sacre Bleu also bears some similarity to how it behaves with Cobalt. The reduction frit got pretty colour and interesting edges, and the TerraNova2 frit developed colours, but mostly in the burgundy/purple range.
Using Sacre Bleu over light colours reveals its true nature. It's not as saturated as Effetre Cobalt, but it is more saturated than Effetre Intense Blue.
Like Effetre Cobalt, Sacre Bleu causes separation reactions in Copper Green, Opal Yellow, Ivory, and Peace.
Here is Sacre Bleu in some fun beads.