LED bulbs and LED dimmer
If the package does not say "dimmable" then it is not dimmable - it might dim and it might not, it might just burn out. 


CREE in their print declares they work with most dimmers. 
Philips bulbs are marked clearly on the package as well.
Other manufacturers like el-cheapos, they are cheap for a reason generally no dimming.


LED's have a frequency driver in them for the power output to "drive" the LED - so what happens is that frequency regulates the power for the LED. 

SOME TRUTH'S ABOUT DIMMERS AND LED's.


Not all dimmers work with LED bulbs.
Dimmers will not necessarily work with all LED bulbs. 
Not all LED bulbs are dimmable.


EDIT 4-30-2017

I have provided the links below for some of the products between Philips and Cree. My personal preference is Cree - they seem to be the all inclusive bulb - compatible with many dimmers, compatible in damp locations (i.e. Showers) and their warranty is EASY. I had a 100 Watter in my garage - it went out - I called them they asked for the model and sent me a replacement - done deal. I also have an older one my daughter dropped and the glass broke - well I trimmed up the glass to the base and use it in my mechanics drop light for working on the car.

Philips Dimmer Compatibility Sheet

Philips USA dimmable-led

Philips USA choose-a-bulb

creebulb.com/dimmers

CREE A-19

Cree Compatible Dimmers