[PyMOL] how to make selected residues blurry?

Dear all,

Could you please check this figure at the following link?
https://drive.google.com/file/d/1Uh9JRh7x0sjv-zGp_0ZKPc1cnWotkZA0/view?usp=sharing

The structure in blue in this figure is prepared from chain A of pdb id 4gms. Some residues are highlighted and look sharp ( as indicated in the figure: 130-loop, 150-loop, 190-helix and 220-loop, and the corresponding residues are:  residues 134-138, 155-163, 188-195, 221-228, respectively), while other part of the structure look blurry. 

I wish to repeat this visual effect but don't know how. I try to select the residues and use "set transparency" command:
    set transparency, 0.8, sele
but it doesn't work.

Could anyone help me figure it out？ With sincere thanks.

Arthur