Business Insider: Google staff are testing a Gemini 4 checkpoint called Carbon that one employee says feels like Opus 5.5 for coding
Business Insider is reporting that Google is internally testing a new Gemini 4 checkpoint named Carbon that matches Opus 5.5 in coding.
Context
If the report holds, Google's next Gemini 4 build could close the coding gap with Anthropic's strongest model, though the comparison is one employee's impression, not a benchmark.
Google announced Gemini 4 Argon on September 30, but the model has not yet reached the public. Business Insider reporter Hugh Langley reported on October 9, citing internal documents and screenshots, that Google employees are now testing a newer Gemini 4 version called Carbon. Andrew Curran, an AI commentator on X, summarized the report.
Deep dive
According to Business Insider, Carbon was made available in recent days inside Jetski, Google's internal coding platform, and may be a new checkpoint of Argon. Curran's post says Carbon matches Opus 5.5 in coding, but coverage of the report describes something softer: one employee told Business Insider that Carbon feels like Opus 5.5 for coding and added that it needs more testing. Another employee wrote internally that Carbon is really good, according to AI Stock Wire's summary of the report.
Business Insider also reported that an internal document shows Google tested a series of Gemini 4 models named Argon, Barium and Carbon, and that a model called Barium B was chosen to become the public Argon, according to coverage by ArtificialWatch and The Decoder. One employee said early versions of Argon felt behind on some coding tasks, closer to Anthropic's older Opus 5.
Business Insider could not determine whether Carbon will ship as an update under the Argon name or as a separate Gemini 4 model, and Google is not guaranteed to release it, according to the coverage. Google declined to comment. No public benchmark for Carbon exists.
What to expect next
Watch for the public release of Gemini 4 Argon, which Google says goes first to trusted testers and then to paid API customers and AI Ultra subscribers, and for any sign that a Carbon checkpoint ships with it.
Independent benchmarks will be the real test of the Opus 5.5 comparison, which so far rests on one employee's impression. Anthropic's and OpenAI's next coding releases will also shape how much ground Google actually gains.