Every time you start a new chat with an AI assistant, you spend the first five minutes re-explaining who you are, what you’re working on, and what tone you want. There’s a better way.

What Is a Gemini Gem?

A Gem is a custom AI persona you create inside Google Gemini. Think of it as a version of Gemini that has already been briefed — on your domain, your style, your goals, and your preferred way of getting answers.

You define the Gem once. From that point on, every conversation you have with it starts from that shared context. No preamble, no recapping, no “please respond in bullet points” at the top of every prompt.

Google ships a handful of pre-built Gems by default — a brainstorming partner, a coding assistant, a writing editor — but the real power is in the ones you create yourself.

How Gems Are Different from Just Prompting

When you open a standard Gemini chat, the model has no memory of what you’ve done before. Each session is a blank slate. Experienced users compensate by writing long system-prompt preambles, pasting in context blocks, or maintaining a personal “prompt library” they copy from.

Gems make that permanent. They act like a saved system instruction that is silently prepended to every message you send, setting the model’s behaviour, tone, domain knowledge, and constraints before you’ve typed a single word.

The difference shows up fast when you’re doing repetitive work — code reviews, weekly summaries, customer response drafts, research digests — anything where the framing and style stays the same even as the content changes.

Creating Your First Gem

Creating a Gem takes about three minutes. Here’s how:

1. Open gemini.google.com and sign in with your Google account.
2. In the left sidebar, find Gems and click Gem manager.
3. Click New Gem (the + button in the top right).
4. Give it a name — something descriptive, like “Python Code Reviewer” or “Weekly Newsletter Editor”.
5. In the Instructions box, write what this Gem should do.
6. Optionally, upload files that give it reference material (style guides, templates, domain glossaries).
7. Hit Save, and you’re done.

The instructions field is where the magic happens. Here’s an example for a developer writing a code review Gem:

You are a senior Python engineer performing code reviews. 
When I paste code, do the following:
- Identify logic bugs, edge cases, and missing error handling
- Note any violations of PEP 8 style guidelines
- Suggest improvements to readability or structure
- Keep feedback concise: use bullet points, not paragraphs
- Do not praise code; focus only on what can be improved

Assume the codebase targets Python 3.11+.

That’s it. Every time you start a conversation with this Gem and paste in a function, you get a focused, opinionated review — without having to write that brief every single time.

What Makes a Good Gem

Not all Gems are equally useful. The quality of the output tracks closely with the quality of the instructions.

Be specific about the task

Vague: “Help me write better.”

Specific: “You are an editor for a B2B SaaS blog. When I paste a draft, shorten sentences over 25 words, replace jargon with plain English, and ensure each paragraph has a clear topic sentence. Output the revised text, then list the changes you made.”

Constrain the format

If you always want bullet points, say so. If you want the response to include a summary at the top, specify it. The more you define the output shape, the less time you spend reformatting responses.

Set the persona

Giving the Gem a character — “you are a sceptical product manager”, “you are a patient Python tutor” — shifts not just the tone but the way it frames problems. A sceptical PM will push back on assumptions. A patient tutor will explain before diving into code.

Tell it what not to do

This is often more powerful than the positive instructions. “Do not suggest tools outside the ones already in use.” “Do not repeat the question back to me.” “Do not use the phrase ‘Certainly!’ or ‘Great question!’” Small exclusions produce noticeably better output.

Practical Gem Ideas

Here are some Gems worth building if you haven’t already:

The best Gems tend to be narrow. A Gem that does one job with precision beats a catch-all assistant every time.

Sharing a Gem

If you’re working with a team, Gems can be shared. From the Gem manager, copy the share link and send it to anyone with a Gemini account. They get the same instructions and uploaded files you set up — a ready-made tool, not a blank slate.

This is useful for teams that want consistent AI output: shared review templates, consistent onboarding materials, standardised customer response tone. One person sets it up; everyone benefits.

Limitations Worth Knowing

Gems are powerful, but they have real constraints:

• Context window cap. Uploaded files and long instruction blocks consume context space. Very large reference documents may be partially ignored.
• No long-term memory between sessions. The Gem’s instructions persist, but facts you told it in a previous conversation don’t. It won’t remember that you “last week mentioned the Q3 deadline was moved.”
• Instructions are not strictly enforced. If you ask the Gem something outside its instructions, it will usually comply rather than refusing. Think of the instructions as a strong default, not an unbreakable rule.

Alternatives to Gemini Gems

Gems are not the only way to build a persistent custom AI persona:

If you’re already in the Google ecosystem — Workspace, Drive, Meet — Gems integrate naturally. If you spend most of your time in VS Code or GitHub, a Copilot or ChatGPT custom GPT might fit better. If privacy and local control matter most, a local model with a saved system prompt does the same job without sending data anywhere.

The Deeper Principle

Gems are really just a UI wrapper around a persistent system prompt. But the wrapper matters, because friction matters.

The difference between a tool you actually use and one you forget about is often not capability — it’s one or two extra steps. Gems reduce the steps. They make the right context available by default, so you spend your energy on the actual problem, not on re-establishing the setting every time.

Build one Gem for the task you do most repetitively. Use it for a week. You’ll be surprised how quickly the briefing overhead disappears.

Which task in your daily work could use a Gem? If you’ve already built one, what instruction made the biggest difference? Drop a note in the comments — the best Gem ideas come from people solving real, specific problems. 👇