Since 2017 Hallmark has been releasing G1 My Little Pony Keepsake ornaments. In 2017 it was Moondancer, 2018 brought us Firefly and 2019 brings us Seashell the Earth Pony. (They did release an ornament in 2014 as well of Cotton Candy)
She's about 2,4 inches tall which roughly translates to 6 centimeters. Right now she's available for pre-order on the Hallmark website. Seashell listed for $15.99 and will be released on July 13, 2019. Have more info below:

Some very big news for the fans of the 35th Anniversary Collector Ponies: Target has listed the Year 2 Earth Ponies and the Year 3 Rainbow Ponies! Although being not available yet it's great to still them still being made after the 35th Anniversary last year. They did change the packaging though as the 35th Anniversary emblem is now gone and replaced with the word "Classic" on the front of the box.