Even on her eighteenth birthday, Dinky received a gemstone from her smarter sister Amethyst. “Magico-thermo-rose-quartz”: useful for igniting campfires away from civilization.

Never toys, storybooks, anything non-practical. Gemstone tools. From a gemstone expert.

Boasting?

Useful though the stones were, Dinky stopped arguing and threw her hooves up.

When she finally, happily, if somewhat uncertainly left home and went to university, she went and stayed far from Ponyville. For five wonderful years, her own mare. Not a patronized child. Not a beloved sister, maybe, but not a patronized child!

Ammy never got as far in geophysics; Dinky became postdoctoral researcher in social sciences. Met tribes, greeted new friends, celebrated countless cities! An endless world of possibilities and freedom beckoned her, blinded her, tempted her to throw herself into something completely different and detached every day.

Regardless, Ammy sent a package every birthday. Always a gemstone. Always functional. Always kept and used, if secretly. Dinky always meant to write back about her amazing adventures, but never did.

Except one year…

Nothing.

Puzzled, uncertain, frightened, Dinky interrupted her sabbatical in the East to trek home. Catch a train home. Gallop home. Burst through the door.

Found Ammy alone.

She’d believed Dinky was never coming back. Why would she? Nothing came back now. Whatever she sent, nothing came back.

Guilt overcame Dinky. She'd kept every gemstone, but never replied. She understood at once. She stayed overnight. Five years caught up with them in five hours. Too little, but thankfully not too late.

Ever since, she unfailingly mailed Ammy "explorer photos" from Qilinland. Notes about temples she’d visited. And all of her love.