Depends what you mean by beautiful? Or ugly for that matter. This brave blog has attempted a list of 100 'beautiful and ugly words'. The writer suggests:
All pretty subjective but interesting to see that there are far more 'beautiful' words on the list than 'ugly' ones. Full list here:
One of the many fascinating features of our language is how often words with pleasant associations are also quite pleasing on the tongue and even to the eye, and how many words, by contrast, acoustically and visually corroborate their disagreeable nature
All pretty subjective but interesting to see that there are far more 'beautiful' words on the list than 'ugly' ones. Full list here: