A dark green stone with light green flecks..hmm, could be jade. But it could be something else too....a quick trip to the jeweler or to a gemologist will solve it! Really, all you need to do is get a specific gravity measurement on it (i.e. a ratio between how much the stone weighs in air versus in water). Jadeite is 3.33 and Nephrite is 2.95.
However, there are a few quick tests & observations you can conduct at home that might shed some light on what you have.
Hold the stone in your hand. Does it feel cool to touch? (You may have seen Chinese or Burmese people touch jade to their cheeks to test its coolness as a sign of authenticity.)
Observe the texture of the material. If there is a fracture, the texture should be splintery and rough. If it shows fairly smooth flat surfaces and "faults" (cleavage planes), you may have another type of green stone. e.g. Amazonite.
If it is polished, does it look like it has a "dimpled" skin? Can you see tiny veining on the surface? If it is translucent, does the material look slightly fibrous?
It's really hard to say what you've got based on your description. As a collector, I'm pretty good at visual ID of jade. If you have a photo, send the url to me and I'll do my best to help!
Me - I LOVE Jade and I'm a gemologist.