Gemini Gems Guide: How to Build Good Ones Before They Turn Into Skills

You've pasted the same 300-word brief into Gemini for the fifth time this month. A Gemini Gem is the fix: a saved set of instructions (plus optional files) that you reopen instead of retyping. They're easy to build and easy to build badly.

There's a bigger piece of news, and most Gems guides online haven't caught up with it. Google has announced that Gems are being replaced by skills. As of my check on 2026-10-08 you can still create and use Gems, but the clock is running. This guide covers how to build a good Gem now, and how to write it so the move to skills costs you nothing.

What is happening to Gems?

From Google's own Workspace help page ("About the transition from Gems to skills"), checked 2026-10-08:

Some of those dates are in the future as I write this, so treat them as Google's plan, not a done deal. I also saw secondary reports that Gem creation in the personal app ends earlier. Google's own page says creation still works until at least those dates, so check whether the New Gem button is still there on your account.

What migration does, per the same page: converts Gems into skills, keeps names, descriptions, custom instructions and uploaded knowledge files, and transfers Drive permissions and sharing settings. Converted skills arrive as inactive drafts that you review and activate. Skills don't sync automatically between the Gemini app and Workspace, so a Gem you want in both places has to be recreated in each.

Skills use the open SKILL.md Markdown format, per Google. If you've read the Claude skill walkthrough, the idea is familiar. This is the practical upshot: write your Gems the way Google tells you to write skills, and the conversion is mostly a copy-paste.

How do I create a Gem?

Steps from Google's Gems help page:

1. Go to gemini.google.com, open the sidebar and click Gems.
2. Click New Gem.
3. Enter a name and instructions. Optionally add knowledge files.
4. Click Save.

There's a "Use Gemini to re-write instructions" button that expands a few words into fuller instructions. I'd use it for a first draft and then cut hard, because generated instructions tend to be longer and vaguer than what you'd write yourself. A Gem you create on the web also shows up in the mobile app and in the Gemini side panel in Google Workspace, per the same page.

To test, use the preview box while editing: type a real prompt and submit. Test with the awkward input, not the polite one.

How should I write Gem instructions?

Google publishes guidance for skills ("Write effective skills for Gemini Apps"). Almost all of it applies to Gems, and it's more specific than the generic advice online. The useful rules:

• One recurring task type per Gem. Google describes a skill as a cheat sheet for one kind of task, not a long manual. A "my whole job" Gem is the usual failure.
• Write for a type of task, not one result. "Turn rough call notes into a client follow-up email" works. "Write the email to Acme about the delay" doesn't survive the second use.
• Match strictness to the task. Creative work can be loose. Exact layouts need step-by-step instructions.
• Include an output template. A section list or skeleton makes formatting repeatable.
• Add a "common mistakes" section. Whatever you keep correcting by hand goes here.
• Say what to do when information is missing. Ask me, or skip it. Without this, the model guesses.
• Name and description. Lowercase with hyphens, starting with a verb. Description under 1,024 characters, third person, ending with a "Use when..." clause. That's Google's skill spec; Gems don't require it, but following it makes the later conversion clean.

Here's a template following those rules. It's untested: I haven't run it in a Gemini account, so run it on three real inputs before you rely on it.

Name: draft-client-followup
Description: Turns rough call notes into a short follow-up email with decisions, actions and open questions. Use when I paste meeting or call notes and want a client-ready email.

Instructions:
You write follow-up emails for a [role, e.g. freelance consultant] to clients.

Steps:
1. Read the notes. Separate what was decided, what someone committed to, and what is still open.
2. Write the email in this order: one-line thanks, "What we agreed", "What happens next" (owner + date for each item), "Still to decide".
3. Keep it under 200 words. Plain language, no filler openers.

Common mistakes to avoid:
- Do not invent dates or owners. If the notes don't say, write "TBC" and list it under "Still to decide".
- Do not promise anything I did not promise in the notes.
- Do not use phrases like "I hope this email finds you well".

If the notes are too thin to write the email, ask me up to three questions instead of guessing.

For the underlying habit of stating the role, constraints and edge cases, the system prompts lesson covers the same ground in more depth. The Gem's instruction box is basically a system prompt you only write once.

What should I put in the knowledge files?

Per Google's help page, knowledge can come from your device, Google Drive, or NotebookLM notebooks. A few practical points:

• Use files for stable reference material. A style guide, a template, a price list. Not for things that change daily.
• Drive files stay live. Gemini uses the latest version of a Drive file, so edits propagate. That's convenient and also a trap: someone edits the file and your Gem's behaviour changes without you touching it.
• Drive needs setup. Keep Activity on and Workspace connected to Gemini Apps.
• Citations can be turned off. There's a "Disable knowledge citations" option, which stops citations to knowledge files. Leave citations on unless the output goes straight to a client.
• File limits. Google's page points to a separate article for supported types and limits and doesn't give numbers. I haven't found those figures, so I won't quote any.

If your use case is studying or researching from a pile of documents, a notebook-based tool may fit better than a Gem. The NotebookLM guide compares the workflow.

Can I share a Gem, and who sees what?

Google's help pages say you can share a Gem or a conversation that used one. The page I could read says a shared Gem doesn't appear in your Gem manager automatically; it shows up under My Gems once you open it and interact with it. The detailed sharing article returned only basic text in my fetch, so I can't give you permission levels (view versus edit) with confidence. Open the Share option on one of your own Gems and read what it offers.

One thing that is documented: after migration, Google says Drive permissions and sharing settings on a Gem transfer to the skill, and you must activate the converted skill before sharing it.

What are the limits?

What Google's help page actually states, as of 2026-10-08:

• You must be signed in to Gemini Apps. Personal accounts must be 13 or older (or the applicable age in your country).
• Gems can't be used with Gemini Live for now.
• The Learning coach premade Gem doesn't currently support language learning.
• Gems may be removed if Google detects a possible violation of its Terms of Service or Prohibited Use Policy. Work and school accounts may be subject to different terms.
• Experimental Gems can vary in quality and availability.

What it doesn't state: which plans include Gems, how many you can have, an instruction length limit, or file count limits. If an article gives you those numbers without a source, be sceptical.

What should I do this week?

1. List your Gems and delete the ones you haven't opened in two months.
2. Copy the instructions of the ones you keep into a plain text file with the name and description rewritten to Google's skill format. That's your backup and your migration prep. Google itself suggests rebuilding critical ones by hand before automatic migration so you can verify the results.
3. Split any Gem that does three jobs into one per task.
4. Watch for the migration notice. Google says it will post full details at least 30 days before migration begins.
5. If you manage Workspace flows, note that new "Ask a Gem" steps can no longer be added in Workspace Studio and existing flows keep working until 2027, per Google.

Gems were a good idea that sat between a pasted prompt and a real assistant. If you want the same pattern elsewhere, ChatGPT custom GPTs and Claude Projects are the equivalents, and the instruction-writing rules above carry across all three.