Thanks Ingela. I thought it was an Eneryda Glasbruk piece, but looks like it is an Eneryda Glass Studio piece instead, if I'm reading it correctly. It might not be clear from the pic. of the mark, but it has Eneryda Glas impressed on the base.
Ivo, its my understanding (with help from more knowledgeable friends), that the piece looks to be 'crizzled'.
I know nothing about this technique personally and have nothing similar to compare it with, but IMHO the bowl looks as though a gather of clear glass has been rolled firstly in powdered blue enamel before being reheated and blown, then rolled in black etc. before being cracked when placed in water. If I've got it wrong, then I've misunderstood the technique. It has a network of clear lines (it just looked white on the pic. because it was photographed against a white background). The surface feels slightly textured around the bottom of the bowl, becoming smoother towards the rim.
This pic. shows the exterior view with traces of blue showing just at the edges of the clear lines. http://i5.photobucket.com/albums/y195/glassie/DSCF58761.jpg
Apologies for wittering on a lot
This picture shows the blue interior. It has a 'powdery' texture look at the bottom. The blue is a deeper colour at the bottom before becoming lighter in the middle section, then darker towards the out turned rim. http://i5.photobucket.com/albums/y195/glassie/DSCF5878.jpg