For all your crafty people out there here's a little idea I tested this afternoon...and it turned out QUITE nicely :) Here's a play by play...
Any Acrylic paint should work decently, but try to choose one that has instructions for glass on it. If you are serious about wanting this painted jar to last you a LONG time then try for Vitrea 160 paint. That's a kind used on cars, etc. Someone online recommended it, I haven't tried it myself.
This part can be a wee bit tricky, but if you want the jar to hold water without paint coming off it's an important step. Rather than submit what worked for me, I'll send you to this helpful link for more detailed information!
See this link for better information on painting glass and baking.
If you are using an antique jar make sure to research what the old glass can handle. How thick your paint is and what type of oven you have can affect this process as well. Trial and error my friends. All I know is after I followed the instructions above, my jar held water just fine :) If sticking a jar in the oven seems too high maintenance or you don't have the right paint...dried flowers can have the same fun effect, and that requires no water..and no baking :)
The last part is easy! Stick some lovely flowers in the jar and gaze at it. I love how the robin's egg blue turned out looking with these pretty pinks. Hope this comes in handy for you....more do it yourself projects coming soon!