Lesson 16 · Advanced · 15 min
Create a custom Gem: team assistant and persistent rules
Build custom Gems in Gemini: lock in permanent system instructions, attach reference guidelines, and distribute specialized assistants to your team.
- Goal
- You will configure, test, and harden custom Gems to automate recurring business tasks using your organization's persistent directives.
- Skills
- Steer
Your first attempt, unaided
Build an 'Editorial Reviewer' Gem embedded with your tone guidelines, and test it against an unedited draft paragraph.
Gems are customized versions of Gemini configured for recurring business assignments across enterprise teams. By combining a fixed persona, persistent system instructions, and authoritative uploaded reference files, you create a specialized workplace assistant without writing code, ready for immediate collaborative deployment across your entire organization.
1Persistent assistants: eliminating repetitive prompt copy-pasting
Persistent assistants eliminate repetitive prompt copy-pasting for recurring enterprise tasks. Storing methodological rules and domain constraints inside a custom Gem ensures every team member receives consistent outputs aligned with organizational standards.
In standard chat sessions, users must repeatedly paste their role, business context, and formatting constraints. A custom Gem preserves these specifications within its immutable system instructions. You can also attach authoritative reference files (brand guidelines, enterprise glossaries, pricing models) that the assistant checks first. Enterprise-grade Gems guarantee dependable outputs regardless of which colleague initiates the prompt.
Gem element Operational role Workplace sales example Name & Description Establishes role and audience « Proposal Auditor: validates quotation accuracy » System instructions Enforces tone, logic, and negative guardrails « Act as a rigorous financial controller inspecting margins » Reference documents Grounded document repository Corporate pricing schedules, Master Service Agreements 
Diagram 'Custom Gem architecture'Diagram generated by AI and reviewed 2Configuring a 'GDPR Compliance Auditor' Gem for cross-functional teams
Configuring a 'GDPR Compliance Auditor' Gem for cross-functional teams illustrates how dedicated assistants scale specialized compliance reviews without overloading internal legal counsel with routine checks.
A corporate data protection officer wants to equip product teams to evaluate consumer intake forms independently.
Weak prompt.
You are a Gem that checks GDPR compliance. Be strict and help our teams.The instructions lack measurable bounds: the Gem returns generic legal definitions without conducting structured procedural checks.
Strong prompt.
You are our company official GDPR Compliance Auditor. For every submitted form, systematically assess: 1) explicit purpose of processing ; 2) legal basis for collection ; 3) mandatory retention disclosure. Respond in a 3-column table: Checked Item, Status (Compliant, Warning, Blocker), and Suggested Remediation. Refuse non-GDPR legal interpretations.The difference. The Gem operates under an explicit audit mandate and an enforced reporting schema, generating consistent compliance reviews on every run.
3Build your first specialized editorial Gem across four structured steps
Build your first specialized editorial Gem across four structured steps to learn how to formalize workplace requirements into an automated assistant for team workflows.
Open the Gem manager on gemini.google.com. Define the title, target persona, core assignment, and explicit negative constraints. Attach a reference guide and test the setup with a realistic scenario.
Run this system prompt configuration:
'Act as the Lead Editorial Quality Reviewer for our marketing department. Rule 1: eliminate all marketing hype. Rule 2: enforce a maximum sentence length of 20 words. Rule 3: present corrections as a 2-column before-and-after comparison table.'
Self-evaluation rubric: (a) the persona and negative rules are saved in system instructions ; (b) stylistic constraints apply on the first turn ; (c) the Gem remains accessible in your sidebar for future work.
4Drafting conflicting or ambiguous guidelines within system setup fields
Drafting conflicting or ambiguous guidelines within system setup fields creates an erratic corporate assistant that produces inconsistent, rambling responses across user sessions.
Entering instructions like 'Be highly creative yet strictly factual, be exhaustive yet very concise' traps the language model in contradictory trade-offs. The Gem oscillates between conflicting styles depending on subtle variations in user prompts.
Fix: establish clear operational hierarchies ('Brevity always supersedes detail; whenever an instruction conflicts, ask clarifying questions').
Rule to remember: crisp, prioritized rules produce a dependable Gem; contradictory adjectives create confusion.
5Quiz
Three questions, instant feedback. Each option comes with an explanation.
6Proof of mastery
Build a custom workplace Gem: provide the full text of its persistent system instructions alongside results from a verification test run.
Criteria
What you wrote at the start of the lesson
Going further
Examine glossary entries for Gem, system instructions, and alignment. The next lesson, Chain complex tasks, explains multi-step orchestration. To manage assistants across your organization, see the Gemini prompt library.
Frequently asked questions
What distinguishes a standard prompt from a custom Gem?
A standard prompt must be pasted anew every session. A Gem durably locks in persona, tonal directives, formatting rules, and reference files permanently.
Can you distribute a custom Gem across workplace teams?
Yes, within Google Workspace corporate tenants, Gems can be shared with designated colleagues or published across your corporate domain.
How extensive can system instructions be inside a Gem?
Gem instructions support thousands of characters, accommodating extensive editorial guidelines, review rubrics, or operational procedures.