What kinds of shifts in supply/demand may account for this implosion in prices?

Learning Goal: I’m working on a economics question and need guidance to help me learn.1. 1.Diamonds are not for ever. See article in Financial Times (Diamonds, a thousand cuts, FT weekend, December 21/22, 2019).What is the market structure in the market for diamonds? The price of diamonds has collapsed since 2011. What kinds of shifts in supply/demand may account for this implosion in prices?2. Pricing Gas in Spain:Mr. Soria, the Spanish Secretary of Energy, announced that his Department was ready to protectconsumersfrom abusive pricing policies by gas companies. Mr. Soria added:
“It cannot be the case thatwheninternational oil prices go up, then gas companies pass on these price hikes to the consumer right away; but when international prices go down, consumers do not profit as quicklyfrom the declining prices…. This is embarrassing to our Nation……” To a first approximation,these pricing patterns areobserved in many otherfree-market countries. Hence, it seems that Mr. Soria is just calling attention to what everyone knows. More specifically,How can we explain asymmetric consumers’ pricing policies in commodity markets? How can we tell if gas companies are making abusive profits?