I have two tables jewelry(j_id,j_name,Description)
and style(style_id,style_name,image)
each table has a many to many relationship with the other table
Not sure that this is a database-design question. To me it looks more like a programming question and in that case it would be helpful to know what programming language and database you are using.
Anyway here is some pseudo code that does what I think it is you are asking about.
Add one row in table jewelry
Store the new jewelry.j_id to a variable @jid
for each @StyleID in SelectedStyleList
begin
Add one row to table jewelry_style
set jewelry_style.j_id=@jid, jewelry_style.style_id = @StyleID
end