Problem: Go to the internet auction site eBay at www.ebay.com and select the category Jewelry and Watches, followed by Loose Diamonds and Gemstones, and then Diamonds, Natural. How many natural diamonds are for sale at the moment? Note the wide array of sizes and prices of the diamonds. In what sense is there competition among the sellers in this market? How does that competition influence prices? In what sense is there competition among buyers? How does that competition influence prices?