The /z/ sound is spelled with <s>, <se> or <z>. The /ʒ/ sound is spelled with <ge> or <su>.
This is a contrast between a sibilant fricative and an alveolar fricative, both voiced and fairly close together in the mouth. The only difference is the way the air is released, through a groove made by the tongue for /z/ and at the front of the tongue for /ʒ/. It can be a problem for many learners and some native speakers. Like the /s/ versus /ʃ/ distinction it is often used by actors to suggest the speech of somebody who is drunk, less often by novelists since the voiced /ʒ/ is hard to represent in normal orthography..
The mean density value is extremely low at 0.1%. The list makes 9 semantic distinctions, a loading of 81%.
baize beige brews Bruges Caesar seizure composer composure eraser erasure erasers erasures liaise Liège loos luge loses luges rues rouge ruses rouges
John Higgins, Shaftesbury, November 2010.