The Queen, during her Silver JubileeThese earrings were most notably worn by The Queen for the big celebration of her Silver Jubilee in 1977 (hence the name I'm using to identify them), when they were paired with her pink Hardy Amies outfit and famous Simone Mirman flower hat. Though the design is along the same lines as her favorites and she wore them in 1995*, this pair of earrings did not make it into the regular rotation. They have remained primarily associated with the Silver Jubilee era.
They're not worn publicly by The Queen today, but this pair of earrings has made it into the group of jewels that she loans to family members.
Five Aquamarine Tiara and the King Faisal Diamond Necklace for the first time, both on loan from The Queen, so we know at least some jewel loaning occurred in advance. The similarity and possibility of an earring loan was noticed by Anna from the Countess of Wessex blog.
The Duchess has since worn them for several occasions (appearances of which I have decided not to list here at this time).Duchess of Cambridge earrings could be on loan by HM as I recall Sophie wearing same ones only 1 time to royal wedding. HM wore those in '77 pic.twitter.com/u97iF39Um5— Kate&Sophie Blogs (@AnnieElizabethN) September 26, 2016
*With thanks to Baxter in the comments!