You can contact Colt Mfg for a production date. I believe they charge a small research fee to provide written documentation. Or you can find a Colt forum on the web & ask its members. The forums often have production date lists on their sites.
1923
made about 1926
Around 1916
made by Colt in 1918.......
made about 1920...........grips unknown
50-500 usd
if it's a New Service model it was made about 1920
about 1923
Check the butt.
Proofhouse.com has a list of serial numbers that can help you.
made by colt in 1918. may have seen service during WW1
correction........made about 1927