How is circumstantial evidence used in determining whether an object was a firearm?

^8. The court in Monjaras also explained: "Most often, circumstantial evidence alone is used to prove the object was a firearm. This is so because when faced with what appears to be a gun, displayed with an explicit or implicit threat to use it, few victims have the composure and opportunity to closely examine the object; and in any event, victims often lack the expertise to tell whether it is a real firearm or an imitation. And since the use of what appears to be a gun is such an effective way to persuade a person to part with personal property without the robber being caught in the act or soon thereafter, the object itself is usually not recovered by investigating officers." (People v. Monjaras, supra, 164 Cal.App.4th at p. 1436.)