What might happen if you go into a store or onto private property with a concealed pistol that has posted a sign saying its a "gun free zone" or "no guns allowed"? Maybe somehow someone notices your carrying or suspects it. Other than asking you to leave, what can they do? Have you committed a crime?
In Texas there are requirements to be legally valid: specific statutory language; specific minimum size; and in both ENlgish and Spanish (IIRC on the last one). Some CHL'ers will ignore an invalid sign, others will not patronize such.
I can understand a jewelry store and a bank due to exigent circumstances. I also don't frequent the insides of those locations often. Frankly if you're gong into a jewelry store your wallet is already about to die...