public IReadOnlyList<string> GetSupportedStrings( 
   SQLStringType sqlStringType
)

using (Geodatabase geodatabase = new Geodatabase(new DatabaseConnectionFile(new Uri("path\\to\\sde\\file\\sdefile.sde"))))
using (Table table = geodatabase.OpenDataset<Table>("TableWithChineseCharacters"))
{
    // This will fail with many database systems that expect Latin characters by default
    string incorrectWhereClause = "颜色 = '绿'";

    // Correct solution is to prepend the 'National String Prefix' to the attribute value
    // For example, with SQL Server this value is 'N'
    // This value is obtained using the SQLSyntax class
    string nationalStringPrefix = "";
    SQLSyntax sqlSyntax = geodatabase.GetSQLSyntax();
    nationalStringPrefix = sqlSyntax.GetSupportedStrings(SQLStringType.NationalStringPrefix).First();

    // This Where clause will work
    QueryFilter queryFilter = new QueryFilter()
    {
        WhereClause = "颜色 = " + nationalStringPrefix + "'绿'"
    };
}