Normally when you are shooting jewellery......which needs time and super detailed eye to the product itself, the charges should be higher than normal product shot. If you are shooting for jewellery you will need to do a little bit of touch up on the photos
Please take note that you will need to have the basic equipments like studio lightings, reflectors, macro lens, glue gun, a good super sterdy tripod with extension tube, toothpicks, hand gloves and chamois leather.
No use charging your friend if you do not have the basics stuff. As you will need to deliver the output of their product. If you want to do it, do it the right way.......with a bit of research.
Since there is about 10 items (most of the time they will add extra 2-3 more), I will charge as per item. I can tell you my LOWEST market rate for jewellery shot is $300.00 per item and it goes up as high as $800.00 per item.
Why charge so high? There are many types and sets of jewellery. Some is just a ring but some are a chain with many diamonds or rubies. I know you are new at this but it does not mean you have to go super low (like $50 per item).
There are no set market rate but if you specialized in shooting products, you will need to charge higher. Never be afraid to charge more if you know you can deliver beatiful shot of their products as clients spend at least a minimum of $15,000 - $20,000 on advertisement alone. Another thing is have a bit of imagination on how much they will earn on their jewellery items once it's sold. Normally they will earn around 30%-35% margine. So if their jewellery is sold at $3,000-$5,000 (they will earn at least $900-$1500). And that's one item only.......
Once last suggestion, try to do a bit of homework by shooting your gf/wife/mom's jewellery at home to have a feel how easy/difficult it is to shoot jewellery. At least you know that when you see your friend's jewellery items, you have a basic idea on how to go about making it look better before charging your client/friend.