Lost gold necklace

I travelled with rwandair from lagos and connected in Kigali to Johannesburg. When they were checking our carry-on bags and scanning us i left my necklace and no one bothered called me back to tell me what i had forgotten when I grabbed my hand bag and left my necklace. It was around 21:50 and I believe there are strict cameras so no one could have taken it please i would like it back it is very dear to me and I would like someone to get in touch regarding how I can get hold of it