https://www.cnet.com/news/original-apple-watch-wont-get-watchos-5-update-even-if-you-bought-the-17000-gold-model/

Traditionally, gold watches are heirlooms that never go out of date. The 18-karat gold Apple Watch Edition, however, is now officially behind the times. 

According to Apple (via Kyle Seth Gray on Twitter) the original first-generation Apple Watch, gold or otherwise, won't get updated to the latest WatchOS 5, announced on Monday at WWDC.