Vɑːz, veɪz or vɔːz

My grandfather would never simply say vase. He was aware of the different pronunciations and so always said vɑːz, veɪz or vɔːz (ie vaas, vaze or vause). My dad would often do it too.

The Century dictionary says

According to the French pron. (väz), and to the time when the word vase appears to have been taken into English (between 1660 and 1700), the reg. E. pron. would be vāz, with a tendency to make it conform to the apparent analogy of base, case, etc. - that is, to pronounce it vās. At the same time, the recency of the word, and its association with art, have tended to encourage the attempts to pronounce it as F., namely väz, in the 18th century absurdly rendered also as vâs, the word being found accordingly in the spelling vause.
If you check this clip on Youtube you will hear Tom Hanks make a referneece tO this about a minute and a half in - https://www.youtube.com/watch?v=pmNmFpJM3qQ