50-500 usd
1968
100-600 USD
if your colt 25 auto is a model 1908 hammerless,it was made in 1927.
100-600 USD
100 to multiple thousands depedning on specifics
.380 1903
300-450 USD
depends of condition
Would need the model to answer.
I would need the Serial Number and Model of the Colt Semi-Auto marked on the barrel. Ivory usually adds $100-$150 to the price if done well or more is unusual with hand working.
To vague a description. Could be worth 500-5000.
COLT MFG. PRODUCED 38 AUTOS FROM 1900 TO 2003. You will need to be more specific with the Model and the serial number of your Colt to learn the exact year of production.