Answer:
If the supply increases the price decreases.
Step-by-step explanation:
If the supply of diamonds increases the price decreases. In fact, one of the reasons why diamonds are very expensive is because it is a scarce commodity in the world and also its extraction and production process has a high cost.
Cecilia can afford to acquire the diamond necklace by the opening of the new mine since the price has decreased and she knows that being a non-renewable resource, when the mine runs out the price of diamonds will rise again and she could sell her necklace and get a profit.