Gemini Watermark: Three Marks, One File
A Gemini image can carry three separate marks, and people usually mean whichever one they can see. Only one of the three is visible, and it is the only one that is optional.
- Watermark type
- Pixel watermark + C2PA metadata
- Hidden characters
- No
- Official detector
- Partial: Partial Checks in the Gemini app and Google Search
- Public API
- Partial: Partial Waitlist or restricted access
- DetectMark support
- DetectMark support: Available Reads C2PA locally
- Removal
- Partial: Partial Metadata strips; pixels stay
- Watermark type
- Statistical text watermark
- Hidden characters
- No
- Official detector
- Partial: Partial Detector portal is waitlist-only
- Public API
- Partial: Partial Waitlist or restricted access
- DetectMark support
- DetectMark support: Unavailable No public detector to call
- Removal
- Unavailable: Unavailable Rewrite only; not a character strip
The three marks
The visible sparkle is a small overlay drawn onto the picture. Since August 14, 2026 it has been a user setting rather than a fixed feature, so most accounts outside the EU can switch it off.
SynthID sits in the pixel values. It is invisible, it is not affected by the sparkle toggle, and it survives the edits people expect to defeat a watermark.
C2PA Content Credentials sit in the file's metadata. That block is readable by any tool that understands the format, DetectMark included, and it can be removed like any other metadata.
Turning the sparkle off does not turn the others off
This is the single most common misunderstanding about Gemini images. The setting controls the drawn overlay. The two invisible marks ship regardless, and one of them cannot be removed at all.
Gemini text
Google says essentially all Gemini text carries SynthID Text, and an independent test on August 23, 2026 found the signal in Gemini 3.5 Flash output. That mark works the same way as Claude's: keyed word choice, no hidden characters, no way to check it from a browser while the detector portal stays waitlist-only.
FAQ
Yes. Google states that essentially all Gemini text carries SynthID Text. An independent test on August 23, 2026 confirmed the signal in Gemini 3.5 Flash output.
Since August 14, 2026 the visible sparkle is a user toggle in Settings under Media Watermark, and it is optional for most users outside the EU. SynthID and C2PA still ship regardless.
A visible sparkle if enabled, invisible SynthID in the pixels, and C2PA Content Credentials in the metadata.
No. SynthID Image lives in the pixels. Screenshots, resaves and crops do not remove it.
It is limited to the Google AI Ultra tier in India, South Korea and Vietnam, and EU accounts do not see the toggle according to third-party reports.
Every check runs in your browser: how it works. The limits are written down too: what DetectMark cannot remove.