Show off your style and make any outfit shine with this simple neopixel jewel necklace.  Customize the code and design your own light effects, and change it up as often as you like to match different outfits or environments.

This is a wonderful intro project for learning to make things with neopixels and microcontrollers.  Get your kids involved -- they'll love showing off their glowing handmade necklace.  


Find a pendant with a translucent or transparent center.  The pendant should be at least 2 inches across.  You can add your own diffusion material or find a pendant that works as-is.  

I found this "black lace" pendant at Michael's craft store a few years ago and it's just perfect for this project.

If you don't have anything appropriate on-hand, you can always assemble the light module and take it with you to the craft or bead store.  They will probably wonder what you're up to, but I imagine that if you're reading this guide, you're already used to that.

Remember to get a necklace cord as well if your pendant doesn't come with one.

This guide was written for the 'original' Gemma board, but can be done with either the original or M0 Gemma. We recommend the Gemma M0 as it is easier to use and is more compatible with modern computers!


1 x LiPoly Battery 100mAh
Small LiPoly battery
1 x Adafruit Gemma M0
Gemma M0 - Miniature Wearable Electronic Platform
1 x Neopixel Jewel
7 Shiny Neopixels
1 x Hook Up Wire
Solid Core Wire in 3 Colors
1 x Battery Charger
Maybe get two of these and keep one in the car.


If you're just starting out and ready to get serious, or if you're tired of using sub-par tools you inherited from your uncle, treat yourself to Lady Ada's Electronics Toolkit.  It's got all the essentials for getting started with electronics.  

A good tool is worth its weight in gold and will save you hours of frustration in the long run.

This guide was first published on May 17, 2017. It was last updated on Jul 18, 2024.

This page (Introduction) was last updated on Mar 08, 2024.

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