An original vintage art glass crystal candle holder or vase, designed by Frank Thrower and made by Dartington, Devon, England. The design originated in 1968 and is FT60. It's square with a wide round rim, and designed as both a vase and to hold a pillar candle on its inner shoulders. It's in the Midnight Grey colouring. The grey was only used from 1967 to 1974 - dating this quite precisely to this late mid century era.
Each side of the cube has an abstract raised daisy flower pattern in the middle, lightly textured. This contrasts with the slim cylindrical narrow neck then wide round rim. Flat polished rim. Mouth blown and handmade so the glass has natural undulations and ripples. 
It's in very good vintage condition with a very slight water mark which is hard to spot (see pics). No chips. 12cm tall x 8cm x 8cm. The inner rim is around 5.8cm wide (so the inner shoulders will support a pillar candle 4 to 5.5cm wide), and the inner hole is about 2.5cm wide. It's very nice.
Free P&P to the UK.