I'm not certified to appraise Asian art and antiques.
If you think you have a valuable piece of artwork and are serious about figuring the value, you may want to find a professional appraiser.
This is not something that can be done remotely by email. The appraiser will need to see the artwork in person. Therefore you are going to need an appraiser in your area.
I suggest you get a referral for a good appraiser from a local museum or gallery. Hopefully they can point you in the right direction, and you'll find an appraiser within driving distance of your home
Expect to pay about $150 for a verbal and $300 for a written appraisal.
The closer you are to San Francisco, London, Hong Kong, New York, or Los Angeles, the closer you are to good Asian art appraisers.
You may want to get an Auction Estimate from Christies of London which apparently is free. They also give referrals for formal appraisals.
I was going complete the Post Graduate Diploma in Asian Art at The British Museum in London just so I could feel somewhat qualified to do appraisals. But as of yet, I have not been able to come up with the $20,000 or the time off from this business needed to complete the courses.
What I am trying to say:
When you consider the cost of an appraisal, consider the cost of becoming a professional appraiser and the education level attained. Or, attend the program at the British Museum yourself, and then do your own appraisal :-)