Re: Value of Colt 25 Vest
That gun is called the Model 1908 Vest Pocket Pistol; that specific gun was made in 1915. Variation in value depends almost entirely on condition. The same type of gun in like new condition could sell for as much as $1200; yours would probably retail for under $200 because it has no remaining finish.
Nonetheless, as you know, they are very reliable and well made pistols and would make a decent defense gun within the limitations of the cartridge. Today, though, there are pistols just as small but chambered for the much more powerful .380 ACP, so .25 caliber pistols have been mostly relegated to collector or keepsake status.