Back around 1994 I borrowed a Genesis game from one of my brother's friends. I do not remember what the name of the game was, or what the label looked like, as it might have been scratched off.

It was a colorful, family friendly side-scrolling platform/adventure game that involved walking right and collecting jewels/gems. The main character was probably human. The game worked in my USA Genesis, it could have been unlicensed, it might have even been an edutainment game.

All I remember from the game is walking right through light sand themed areas collecting gems/jewels.

I've gone through lists of Genesis games multiple times and nothing sticks out, almost as if the game doesn't exist.

Note: It was not Sonic, Joe & Mac, Adventure Island, Chuck Rock, or Jewel Master.

Maybe an unbranded version of McDonaldland Adventure by Treasure?

Looks fun, but I'm quite certain that's not the right game.

I don't know why but, even though not everything matches, it makes me think of Cool Spot. That 7up game.

Thanks for the suggestion, but it's definitely not that game. I remember seeing that in magazines, but I've never played that before.

Here's a suggestion that is not what you are looking for, but may help:

Look for Genesis Hidden Gems videos from Metal Jesus Rocks and/or the Genesis videos made by SNES Drunk.

They go over a lot of Genesis games and you may happen to find the game you're looking for. And, besides, the videos are mega fun to watch. :)

Kid Chameleon maybe?

The first level of Puggsy is called The Beach,

You should also check out Dynamite Heady and Decap Attack.

The first thing that came to my mind when you mentioned collecting jewels is High Seas Havoc. Then I remembered that Rocket Knight Adventures and its sequel, Sparkster also involve such trinkets.

What about Ristar, that is an overlooked game with a very family friendly visual.

...

MJR has quite a few of those, you may want to check if you missed one of them.

Also, if you have the patience, maybe taking a look at the genesis games in each episode of Game Sack listed in www.gamesack.net/gamesack.html

Who knows? Maybe one of the names will trigger some memory.

Can it be Socket? You are not collecting gems but it is a colorful sidescroller platformer.

Fantastic Dizzy?
Bubsy or Bubsy 2?
James Pond 1, 2 or 3?
Aero the Acrobat 1 or 2?
Zero the Kamikaze Squirrel?
Adventures of Yogi Bear?
Mr. Nutz?