All the 6,000 medals for the 2008 Olympic Games have arrived in the capital from the Shanhai Mint,ready for their debut on August 8.For the,first time in Olympic history,the medals for the Beijing Games mix metal and jade. The technology of inlaying jade into metal can date back to the Han Dynasty almost 2,000 years ago.It is not easy to bond jade perfectly with metal.The key to the process lies in the inner layer of the metal and the groove of the jade ring.A seal ring is put between the inner layer and the groove to join the metal and jade together. Jade rings used for casting Olympic medals have been subjected to strict quality controls,and those not up to the standard have been thrown away. To make use of those jade rings that do meet the quality criteria,metal medals were produced to fit the jade tings,and more than ten different sizes of seal rings were designed. To avoiding any loosening of the jade rings due to aging of the seals,glue has been used in casting the;Olympic medals,which is a painstaking manual process. Experts from the International Olympic Committee(IOC)were concerned about the risk of fragility when the jade ring design was proposed.The IOC required that jade rings should be strong enough to withstand a 2-meter drop test.The Shanghai Mint raised that standard to 3- meters.Medals call survive a 3-meter drop test with only minor cracks on the jade rings. The medals for 2008 Olympic Games are different from those of the past games in which they  _  .
are made of pure gold are more valuable mix metal and jade are made in different cities