Cartier Tank Must Watch, Small Model, SolarBeat Photovolta
at RRP level
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ℹ️ 1-month trend
Price change over the past 30 days. Shows the short-term market movement — relevant if you want to buy or sell soon.
ℹ️ 4-month trend
The central metric behind the momentum score. It filters out short-term swings and shows the true, medium-term market trend of this reference.
ℹ️ Volatility
Annualised price fluctuation. Below 10 % = very stable, 10–20 % = normal, above 20 % = volatile. With high volatility the price can change quickly — in both directions. Be cautious about buying without checking the current price.
ℹ️ Momentum score
ChronoCheck's own indicator from 0 to 100, calculated from the 4-month trend, volatility and market direction.
- Above 60 — Upward trend. Good time to sell, prices are rising.
- 40 – 60 — Neutral. Stable price level, no pressure to act.
- Below 40 — Downward trend. Wait or enter at a good price.
ℹ️ Investment Grade A/B/C/D
ChronoCheck's own rating for each reference. A 0–100 point scale, made up of four weighted components:
- Momentum (40 pts) — trend strength from the momentum score.
- Liquidity (25 pts) — number of active live listings.
- Stability (20 pts) — inverse volatility — the calmer, the better.
- Source robustness (15 pts) — number of independent market sources.
- A · 75+ Trend is right, liquidity good, data broad.
- B · 55–74 Solid, but one component weaker.
- C · 35–54 Average, volatility or market breadth weigh on it.
- D · below 35 Downward or too little data — a collector's piece.
Not investment advice. Pure data analysis from aggregated market sources.
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Technical data
Cartier Ref. WSTA0121 — Variants and collector names
Known as: Tank Must SolarBeat Small Bracelet, SolarBeat Tank Small, Tank Must Solar Bracelet
Production phases and changes
- 2021: Market launch of the Tank Must SolarBeat Small with steel bracelet (WSTA0121), released in parallel with leather version WSTA0119 and large models WSTA0059/WSTA0060
- 2024: Silent V2 update from November 2024: full-surface microperforation, integrated photovoltaic cells in the movement, runtime on full charge 5 months → 2 years
Bezel variants
- WSTA0121-Bezel-Steel-Polished
Dial variants
- SolarBeat V1 Dial — Roman numerals, micro-perforation on numerals only (photovoltaic)
- SolarBeat V2 Dial — Roman numerals, full-surface micro-perforation across the entire dial
Crystal variants
- Saphir-TankMust-Small-AR
Bracelet variants
- Tank Must SolarBeat Stahlarmband Ref. WSTA0121-Bracelet-Steel-Folding
April 2021: Cartier unveils the new Tank Must generation, and with the SolarBeat, brings a photovoltaic movement into the collection for the first time. Reference WSTA0121 is the steel-bracelet version in the small case, launched alongside the leather-strap WSTA0119 and the two larger models, WSTA0059 and WSTA0060. Cartier backs the movement with an 8-year warranty, and battery changes become a thing of the past. Among collectors, the watch goes by the informal names Tank Must SolarBeat Small Bracelet or simply SolarBeat Tank Small, though Cartier's official nomenclature remains WSTA0121.
## The Quiet Generation Change of November 2024
With no press release and no new reference number, Cartier swaps out the movement's internals starting in November 2024. The micro-perforation now spans the entire dial surface, and the photovoltaic cells sit integrated directly into the movement rather than mounted on top. The practical difference: a full charge lasts around 5 months on the V1, versus 2 years on the V2. Reference WSTA0121 stays the same, and Cartier has never officially communicated a V2 launch.
## V1 or V2 — It Comes Down to a Close Look
Anyone buying a used WSTA0121 can narrow down the production year by checking the date on the user guide: anything after November 1, 2024 is very likely running the V2. But only a dial inspection under a loupe gives certainty — uniform micro-perforation versus the V1's localized pattern. The polished steel bezel element remains identical across both generations, so it offers no way to tell them apart.
Brand profile: Cartier
Cartier watches (Santos, Tank, Ballon Bleu) are popular targets for counterfeiters. The distinctive design (Roman numerals, blue sword hands) is recognizable — but also easy to copy.
- Sapphire cabochon crown: on genuine pieces it's SET INTO THE METAL (bezel-set); on fakes it's usually GLUED. Test: loupe — adhesive residue around the edge = fake.
- Bracelet screws: genuine Cartier bracelets ALWAYS have visible screw slots. Pins instead = fake.
- 'Swiss Made' at 6 o'clock: MICROPRINTED directly beneath the 6 o'clock marker. Fakes often omit it or print it crooked.
- Guilloché pattern: under 10x magnification, EXACTLY parallel and uniformly deep. Irregularities = fake.
Serial number format: Cartier serial numbers: alphanumeric, on the case back. Older models: number located between the crystal ring and the case. New purchases come with a Cartier passport.
Further sources
Buying guide: Cartier Tank Must Watch, Small Model, SolarBeat Photovolta
Entry into Cartier
At $4,759 this reference is one of the more affordable ways to wear a Cartier on your wrist. That is precisely why many pieces have already passed through several hands — condition varies accordingly. Buyers here should pay particular attention to service history and honest photos from the seller.
Watch out for swings: This reference has an above-average volatility of 186.7 percent. In concrete terms: the price can move by several hundred euros within a few weeks. Check the current value before buying or selling — old listings or auction results from two months ago are of little help.
What to look out for when buying?
- Authenticity: The serial number and reference on the case must match the papers. A professional authenticity check of the Cartier Tank Must Watch, Small Model, SolarBeat Photovolta reliably rules out counterfeits.
- Condition: Check scratches on the case and bezel — professional refurbishment can leave traces.
- Service history: A documented service by the manufacturer or a certified watchmaker increases the value.
- Scope of delivery: Box, papers and warranty card make a noticeable price difference on the Tank Must Watch, Small Model, SolarBeat Photovolta.
- Independent certification: The CPS-52 standard covers 52 checkpoints — from the serial number and the timing machine to water resistance. The result is secured on the blockchain and can be verified at any time.
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