One of the great new populations of consumers are "tweeners" those that are not "really" still little kids but aren't quite teenagers yet either. Typically, ages 10-14 (since 14 is still pretty young, middle school age, not going out with others, etc).

First, there are a few websites out there that are specifically developed and maintained for youth to shop safely online. Most have a spending limit determined by adult intervention, so they have a set amount they can spend. Money can be added to their "stash" weekly, on special days (birthday, etc), or on an occasional basis, by the parent/guardina. These sites are great for promoting goods targeted to their age groups. One possibility is http://girlslikestuffstore.com but there are others, try google search on youth online shopping sites, topics similar to that.  Another is http://www.karmaloop.com .  The one I've been on the most is http://www.shoplikeanna.com/ . 

 One wonderful way to get your designs in front of girls is to have a jewelry making activity at birthday parties, slumber parties, etc.   Girls are always looking for things to do at their party that will be fun and unique.  Getting to design your own bracelet can be a great thing to offer.  Rena Klingenberg has a hub on Birthday Bracelet Party hub here, search on her name and it should come up.  In fact, I follow her to be contatcted when she writes a new hubpage, so you may find her that way.  Rena has been designing jewelry for a long times and has several interesting posts on the internet.

This is an area I am working on developing myself.  One way to market these is to post notices where moms and youth are:  on bulletin and cork boards that are there for open posting, an advertisement in a school bulletin or school publication (the booklet given at the high school season sports final, or for the band event, etc). 

Even a free posting on craigs list for your area may result in contacts.  Rena shows an example of a flyer she has developed, but I am also planning on putting together a small label that I can affix to the back of my business cards.  For this, you can even print simply publisher flyers and stick them under windshielf wipers at grocery stores, etc. 

Set up a price for each child, to be paid before the activity begins.  Offer girls color, shape and size choices, so they can design their own unique piece of jewelry.  Include a small organza or silk bag for them to keep their new braclet in.  Such an activity shouldn't take over 2 hours, leaving you with the potential of a couple of hundred income for 2 hours work.  They lay out their design, or string it on pre-formed wire that has your toggle/clasp on one end, then you can fairly quickly finish it to fit.

 One last niche market for your jewelry are grandmothers, or aunts, etc that buy gifts for girls.  Especially if they don't share the same tastes/styles or if they simply don't keep up on what jewelry is "hot" or trendy right now.  This group can come to you and your store as a resource.  So, watch for blogs or social marketing sites where you can be a resource.  This isn't a blatant promotion problem but one where, if you work on being a good resource for other things and asking members to be a resource for you, it wil naturally happen