The /ɔɪ/ diphthong is spelled <oi> and <oy>. The /əʊ/ diphthong has many spellings including <oCe>, <oe>, <ow> or <oa>.
This is a contrast between two diphthongs with different starting positions and different directions of movement. It is not a problem for learners.
The density figure is high at 11.7%. The set makes 42 semantic contrasts giving a loading of 45.7%.
alloy aloe alloys aloes boil bole boils boles boil bowl boiled bowled boiling bowling boils bowls boiled bold boiler bowler boilers bowlers boy beau boys beaux boy bow boys bows buoy beau buoys beaux buoy bow buoys beaux buoyed bowed buoying bowing buoyed bode cloys close coign cone coigns cones coin cone coins cones coined coned coining coning coil coal coiled coaled coiling coaling coils coals coy Co foil foal foiled foaled foiling foaling foils foals Fowey foe groin groan groined groaned groining groaning groins groans hautboy hobo hautboys hoboes hoist host hoisted hosted hoisting hosting hoists hosts join Joan joy Jo Lloyd's loads loin loan loins loans moil mole moils moles moiled mould moist most moistly mostly noise knows noise nose noised nosed noises noses noising nosing noisy nosey noisier nosier noisiest nosiest oiled old poise pose poised posed poises poses poising posing quoit coat quoits coats Roy roe Roy rwo soil sole soiled sold soiling soling soils soles soy so toil toll toiled tolled toiling tolling toils tolls toiled told toy toe toying toeing toys toes toyed toed toyed toad voile vole
John Higgins, Shaftesbury, December 2009