Seriously?
Obviously the necklace would be returned to the Wayne family almost immediately. At most, the police would note their location when they dropped to the street (for forensic reconstruction, if necessary).
I don't know where you guys get this idea that the police would keep it as "evidence." Evidence of what, exactly? Unless they contain Chill's prints (which they don't) or DNA (unlikely), they wouldn't serve as any form of "evidence" of who the murderer was, any more than any of the clothes that Bruce or the Waynes were wearing, and so they wouldn't be "kept" for any reason! Just because a physical object is present at a murder scene, doesn't mean it's kept by the police or that it's considered evidence. (Do you think the police stripped Bruce bare naked because his clothes were "evidence" simply because they were present at a crime scene?)
So given that the Waynes were the rightful owners, they'd have the pearls returned immediately. I don't think it's a stretch that Alfred had the necklace reconstructed, as a keepsake for Bruce to remember his mother by. Or maybe Alfred didn't reconstruct it - maybe they were kept in a little box and, years later, Bruce himself decided to have it reconstructed as a keepsake.
NO. HE'S NOT.
That's the glare of the glossy magazine in a poor photo that used a flash, combined with lossy JPG compression.
You guys are SO eager for new information that you're inventing it out of pixels now.
Get a grip!
