The /eɪ/ diphthong is spelled <aCe>, <ai>, <ay> or <a> in the homograph bass. The /ʊə/ diphthong is spelled <our>, <oor> or <ure>.
This is a contrast between two diphthongs. The starting positions are well separated and the direction of movement is different. Confusions are unlikely.
Interesting pairs include:
The density figure is 1.99%. The set makes 13 semantic contrasts giving a loading of 61.9%.
allay allure allayed allured allays allures amaze amours baize boors bane bourn base bourse bases bourses bass bourse basses bourses bay boor bays boors daily dourly lay lure lays lures made moored maid moored may moor Mays moors pay poor spay spoor spays spoors
John Higgins, Shaftesbury, December 2009