For anyone on PC who would like to give modifying the game with the Creation Kit a try, I figured I'd give a quick example of how to do a small but (I think) useful edit. In this case, I hate that those Unusual Gem / Stone of Barenziah are quest items that have weight and can't be dropped. So a simple fix is to go make them weightless.
Installing Creation Kit
First, download the Creation Kit from Steam. Go to your Library, choose View-> Tools, and look for "Creation Kit" in the list, and then right click to install it. Once it is done, right click and Play.
It will launch with a background window and 3 smaller windows, one for objects, one to view Cells (locations) and a render window.
Select the Data file the object is in
First thing is you need to select which data file you want to view. So in the big background window, click on File -> Data. There are probably only two Plugin/Master Files available unless you have a lot of mods. Double click on the Skyrim.esm Master File and say Ok. It will give some warnings about problems it found in the file, just hit Yes to All to skip them.
Find the object to edit
Now we've essentially loaded every object in the game. Finding the right one can be a pain. The simplest way is to go to Edit -> Find Text and do a search for what we're looking for. So put: Unusual Gem in the search box and hit Find Text. The different matches are split out by info, scripts (programs), Objects, quest stages, etc. Click on the Objects tab and we see there is a MiscItem type of object named "TGCrownGemInventory (0009DFBB)". The TG stands for Thieves Guild, a lot of objects and scripts get something like that put in the name so you can tell what they are part of. You can double click on the row right there to bring up the editor for the item, but first lets go look at the item in the Object Window.
Click on the Object Window. On the left under filter look for Items -> MiscItem. Click on the word MiscItem and then scroll down on the right to find TGCrownGemInventory. You could also just type tgcrown in the Filter box top left to cut the list down.
So you can see some stats for it here. There are 24 of them in the game world. The Model is the actual image used for its appearance in game. Name is "Unusual Gem". And Weight is 0.5, our culprit.
Ok, now double click on the item, either in the Object Window or the Text Search window. The only parameter we want to change is the Weight, changing it to 0.0000 and then hit Ok.
Save our edits to a new plugin file
Now the last thing we need to do is save a plugin file that has our edit in it. In the main window click on File-> Save, or just hit the Save icon. It will save it as an .esp. I'm going to call it Barenziah_zero_weight, and let it write it into the default directory, our Skyrim/Data directory where it needs to go.
The Kit will only save new or edited things into the file. So it's not making a file with a copy of everything in it. It's making a file with just our edited Unusual Gem in it.
It is possible to save the edit to an existing file. If we wanted to edit our file we just made, we would select it in our Data files when we first run Creation Kit, and we would use the "Set as Active File" button in that window to tell the game we want to save the edit back into the existing file. Don't ever set the original Skyrim.esm as your Active File. I'm not even sure if it will let you, but you always want to create your own plugin, or edit an existing plugin, not create a whole new copy of the original as that is unnecessary.
Now tell the game to include our plugin
Simple step is now we run SkyrimLauncher and click on Data. We should see our plugin file in the list, and it looks like it added it in automatically when we did.
This is how the game loads objects... first it loads all objects in Skyrim.esm, the master file. Then it loads any files in its data file list (which we just added our plugin to). If it loads a copy of an item, then finds the same exact item in a later data file, the last one in wins and overwrites the others. So Skyrim.esm always gets loaded first, so our plugin loads after it and our edited Unusual Gem will overwrite the original Unusual Gem. But the original is still there, so if we ever wanted to undo our change we could just remove our plugin file, or even just deselect it from the list of Data files.
That's it. Then run the game and check your inventory and you should see any Unusual Gem or Stone of Barenziah as being 0 weight.
By the way I'll add, I'm not 100% certain how they get the name to change from "Unusual Gem" to "Stone of Barenziah" like that. I actually searched for both, expecting to find different items with both names. But in looking at the quest script, I see some things about name aliases going on that must be doing the rename, I just don't understand how it works fully. That's part of the

fun, is getting to look at scripts and things and see how they work.
I would caution against doing a lot of poking and then saving a plugin. You don't want to inadvertently change something you didn't mean to. So when actually making a plugin, I'd just go change whatever things I meant and save it, and don't go exploring in that session.