No way to offer anything beyond what you have already told us until we get pictures. At taht point, it may be possible to offer more. Esepcially folks like Bob from Saint Looie.
A quick check in Pistols of the World (useful but NOT, for certain, exhaustve - it misses many models and variants) indicates that Orbea Hermanos was founded in 1859 and produced (along with Lefaucheux-type M1858 pinfires) a gas-operated revolver (I'd like to visit the Museu de armas in Eibar and see that one) in 1863. Also made Kerr-type cap-lock revolvers of he M1862 navy type, and a copy of the S&W No. 3 Russian for the Spanish Army in the late 1870s and then an 11mm `Revolver Smith y Wesson refomado no.7' and other revolvers of both Colt and S&W patterns.
Models listed included the Colon, a 32 based on the Colt Police Positive, from 1925; Iris, in 32-20, 32 Long and 38 Special, a 6" barreled, square butt style; Model 1915 for he italian Army, i 11.35mm and absed on the large-frame S&W Top-break design; O.H. series, all carrying the OH trademark and based on S&W Military & Police pattern, and found in 32, 32-20, 8mm French, and 38 Special, plus a few known in 5.5mm Velo Dog (unusual chambering for a modern revolver). As you can see, essentailly impossible to guess what you have without at least photos with some reference as to dimensions.
Absent comrades (sound of breaking glass)