I mattified the polish the same day I did this, which was a few days ago. I used China Glaze Matte Magic, and it seems like the matte effect gradually fades. Especially if you use lotion and oils. But the matte effect is still some what there. I don't matte polishes very often due to this.
The actual polish color I used is Sally Hansen Salon Manicure (i think?) in Fairy Teal. Love the color. I dread taking it off though, it always stains my nails regardless of the base coat I use.