我觉得这两句话都不对.rich是形容词,不能用作名词形式,所以不能说my precious riches.建议可以用同意名词treasure,也是财富珍宝的意思.而且第二句话从句which 后面没有谓语动词.这两句话可以写成：
1.You are my precious treasure in my life
2.You are the treasure which is precious in my life.