Just a selection of colour paletes I've gathered from around the web. For use with Apple's colour picker tool.
A lot of these are taken from places over the internet. I'll name most of them where they're from unless that's just not possible.
- Material Design Colors from https://www.materialui.co/colors more details https://material.io/guidelines/style/color.html
- Flat UI Colors from https://www.materialui.co/flatuicolors
- Social Colors from https://www.materialui.co/socialcolors
- Metro Colors from https://www.materialui.co/metrocolors
- HTML Colors from https://www.materialui.co/htmlcolors
- Kuretake Real Brush Colors from http://www.cleancolor.jp/RB-6000AT.html (written in Japanese) product page: http://www.cleancolor.jp/lineup.html (written in Japanese, too)