I suggest you to wear the colored contact lenses which may help your blue eyes look more gray. You can choose the dark gray color. In addition, they will make your eyes look charming and beautiful. However, you should keep the habit of hygiene, not letting your eyes get infection from dryness or dust or sand.
If you want to make your blue eyes look grey, the most and convenient way is wearing colored contact lenses. You can choose grey colored contact lenses that to enhance your look. By this way, you can make your eyes become any colors. You can just pick up one that you like it. Just go ahead.
It depends on you wanna change your eyes color permanently or temporarily. Colored contacts and laser surgery can realize your dream respectively.
For me, I would like to try colored contacts. It is a simple way to know whether the grey makes you more attractive. If you do not like it, just forget about it.
As for laser surgery, a California doctor has developed a technology of laser that can change eye's color from brown to blur last year. But that surgery could also potentially damage eyes.
I believe, with the development of modern science and technology, the surgery could give your blue eyes more grey in the near future.
At last, I strongly recommend colored contacts. Do not to be test specimen!
Wearing cosmetic contact lenses is the only way for you to make your eyes more grey. If you are not myopic, you can wear contact lenses of zero degree. But if you are myopic, choose the right prescription contact lenses. You can choose different colors of contacts on your own in the glasses shop. And I just want to tell you that so far there is no other ways to make your eyes more grey naturally.