The parachute effect on solitaire diamond rings

Saturday night and Sunday morning I tried to recover a very expensive diamond ring in the wet sand, the couple who lost the ring offered me a $1000.00 cash reward and I was out the door like a flash. 
Unfortunately I could not find the diamond engagement ring that was lost earlier on Saturday morning. 
I believe the couple had the correct area the ring was lost, but the ring either sank out of sight, or got washed into the water. 
They told me several people had dug around in the wet sand trying to find the ring, my guess is that someone stepped on the ring and pushed it further down into the mushy sand. 
I used my CTX 3030 with an 11 inch search coil first then covered the same area using my 17 inch search coil for added depth, but I still could not find the ring.
My next searches will involve using smaller search coils and hoping for a little beach erosion in the area where the ring was lost. 
I believe gold and platinum rings with large diamonds are difficult to find because of their shape. 
They do not lay flat like normal platinum or gold bands,  in my opinion the large diamond acts like a parachute and flips the ring down and on edge making it more difficult to detect. 
Gold or platinum bands with large solitaire diamonds are not usually wide, they are thin bands. 
If large diamonds in typical prong settings cause the ring to parachute, you are trying to detect a small section of the band.
I have recovered several nice diamond rings and gold chains this year,  and I credit my ultra slow sweep speed for making it possible to recover them. 



This is the fourth lost expensive diamond ring story I have heard this year, I wonder how many expensive diamond solitaire rings are lost on the beach every week?
I know all of these lost ring stories has caused me to cut down on the amount of discrimination I use in trashy areas, just in case.