It looks like someone has re-done a pre war Colt revolver. It is hard to put a value on a non original gun as it will mean more to some buyers than it will to others. It looks like it was well done and if the value is for insurance purposes I would think about $2500-$3000 should do it. It may or may not bring that on the open market.
At a glance, I am thinking, an 'Official Police' or maybe an 'Army Special', which someone cut the Barrel down on, and, fitted a Universal Slip-On Sporting Rifle style Front Sight...and, a wide Trigger. Where, the Revolver was then Engraved, Gold inlaid, and, re-Blued, and, fitted with aftermarket Mother of Pearl Stocks which have been Checked/Checkered ( I can not tell if these are solid MOP or if they a layer on some substrate material though).
Can you post some additional views? Showing the top and other side and rear of the Grip?
Some here may be able to propose where this style of Engraving may have come from.
I am thinking it is European, myself...but not German.
Can you relay to us the Serial Numbers ( last digits as "X"s is fine ) as found inside the Knuckle area of the Crane? ( Visible when the Cylinder is all the way open ).
From the shape of the trigger guard, I'm thinking Police Positive. From the rounded grip frame, I was thinking Detective Special but the ejector rod is the same length as the barrel, but they did make them with 3" and 4" bbls too.