I believe the technique for your two 'petrol' blue vases would be called Battuto. But I have to say, if I found two vases of a matching style in a charity shop, I'd be concerned they modern representations and not attributable to one particular designer. I know from experience that battuto style vases have appeared in TKMaxx, and although I was sorely tempted, I didn't purchase (I have enough glass to sink a battleship as it is!) .
Maybe someone with a better knowledge than me might be able to assist?