Reproduction Martha Washington necklace sold exclusively through George Washington's Mount Vernon Gift Shop. It is available on-line. You can also find earrings to match them as well.
Disclaimer - Please note that I was not included in the photography sessions of the artisan's work, so had no way to consult in the context and how it was shown in the magazine. It would not be worn, nor dress up, a farm girl's clothing unless she stole it! But it would be worn by a prosperous middling, gentry, and/or royal lady. Martha Washington wore just such a one in actual garnets. My reproduction is paste (rhinestones/crystal).
Another of my items, a Forget Me Not Reproduction Flower ring was also accepted, but not able to be shown in the magazine. You can find this ring available in my Etsy shop as well as George Washington's Mount Vernon gift shop (soon to also be available on-line).