Our raspberry glaze at the BMCA clay studio is gorgeous deep red, with some blue tinges here and there. It works well as long as you honor it's limits.
Too drippy to be on with another glaze near the bottom of a pot...guaranteed to run onto the kiln shelf. Gorgeous all by itself
And now I know she just (being persnickity, must be female, raspberry) won't paint onto anything either. I tested it about 6 times, painting little orchids onto the clay, then firing at cone 6 (all our glazes are geared for that temp). They came out grey and fluid looking. And I learned the drippiness of the glaze means it blends like a watercolor, completely without control, when other glazes like white or yellow are added. These were on a verticle surface and I knew too much of raspberry would run downhill. I just didn't know that all the red in it would run away too!