三级认证

The marriage certificate need authentication from following authorities
1. Secretary of State of CT,
2. US State Department,
3. Chinese Consulate in NYC

See 三级认证 section in following links.

http://www.chinaconsulatesf.org/chn/qianzhen/gzrz/#introduction_authentication

http://visa.ywpw.com/authentication/index_gb.html