Ask two suppliers what their “alexandrite laser” is and you may get two different answers. The word describes a gemstone crystal, chromium-doped chrysoberyl, that produces laser light when it’s energised. It’s also shorthand for the wavelength that crystal emits (755nm).
Spec sheets tend to blur the two, so a pair of platforms sold under the same label can be very different machines inside, with different running costs, servicing needs and treatment speeds.
What Is an Alexandrite Laser?
An alexandrite laser is a solid-state laser that emits light at 755nm. Its gain medium is a chromium-doped chrysoberyl crystal, which is pumped by a flashlamp with intense bursts of light until it produces a coherent beam. It’s the same basic architecture as a flashlamp-pumped Nd:YAG laser, just with a different crystal and a shorter wavelength.
Pulse duration changes what the 755nm wavelength does in tissue. Long-pulsed alexandrite lasers fire in milliseconds. That’s long enough to heat a hair follicle through its full depth, which is why this is the regime used for hair removal. It’s also used for some pigmented and vascular lesions.
Q-switched and picosecond alexandrite lasers work in nanoseconds or trillionths of a second. At those pulse durations, the effect is photoacoustic rather than purely thermal, breaking pigment into particles small enough for the body to clear. This is pigment and tattoo territory. Cynosure’s PicoSure® Pro is the well-known 755nm picosecond device, and we look at how it compares with other picosecond platforms in PicoStar vs PicoSure vs PicoWay.
There’s now a third route to the same wavelength band, and it has changed the market. High-power diode arrays can emit in the alexandrite band directly, with no crystal and no flashlamp involved. So “alexandrite” on a spec sheet may describe a source, or it may describe only a wavelength.
Why 755nm Works for Hair Removal
All laser hair removal rests on a principle called selective photothermolysis. You choose a wavelength that the target absorbs far more readily than the surrounding tissue, then deliver it in a pulse short enough for the heat to stay roughly where it was absorbed. The target is damaged while heat exposure to the surrounding tissue is limited. In hair removal, that target is melanin in the hair shaft and bulb, and the heat it absorbs spreads to the surrounding follicular structures responsible for regrowth.
Melanin absorbs strongly across the visible and near-infrared spectrum, but its absorption falls steadily as wavelength increases. At 755nm it’s high. Using the widely cited optical model of melanin absorption, 755nm is absorbed roughly a quarter more strongly than 810nm and about three times more strongly than 1064nm. That efficiency is why alexandrite-band light performs so well on fine and lighter hair, which carries less pigment for the laser to work with.
The trade-off sits in the epidermis. Melanin in the skin absorbs 755nm just as readily as melanin in the follicle, so in darker skin more of the energy is taken up at the surface before it reaches the target. That raises the risk of burns and pigment change. It’s why the alexandrite band is best suited to lighter and olive skin, roughly Fitzpatrick I to IV, with type IV requiring more conservative treatment and strict tan avoidance.
[Diagram: Relative melanin absorption at 755nm, 810nm and 1064nm] Simple bar chart with 755nm set to 100. 810nm ≈ 78, 1064nm ≈ 30. Caption: “Relative melanin absorption, calculated from Jacques (2013).” Alt text: Bar chart showing melanin absorbs 755nm light most strongly, 810nm slightly less and 1064nm least.Alexandrite vs Diode Laser: Same Wavelength, Different Source
If a diode platform delivers light in the alexandrite band, does it treat hair as well as a crystal alexandrite laser? The published comparisons suggest it does, though the evidence base is small and each study is worth reading for what it tested.
The longest follow-up comes from a split-axilla study published in Dermatologic Surgery in 2001. Fifteen patients with skin types I to V had one half of each underarm treated with a 755nm alexandrite laser and the other half with a diode laser. They received four treatments at four- to six-week intervals. At twelve months, the alexandrite and diode lasers achieved 85% and 84% hair reduction respectively. The diode in that study emitted at 800nm rather than 755nm, so it compares source types more than an identical wavelength.
A randomised, assessor-blind trial published in Lasers in Medical Science in 2019 closed that gap. Sixteen women with skin types III and IV received six sessions, with a 755nm diode on one underarm and a 755nm alexandrite laser on the other. Six months after the final session, hair counts had fallen by 33% on the diode side and 35% on the alexandrite side, a difference that wasn’t statistically significant. The authors concluded the 755nm diode was as effective and safe as the 755nm alexandrite laser in these skin types. The secondary measures went the other way, though. Blinded assessment of before and after photos and patient satisfaction were both significantly better on the alexandrite side.
A side-by-side pilot in the Journal of Cosmetic and Laser Therapy (2015) reported 88.8% hair reduction with a 755nm diode against 77.7% with a scanned 755nm alexandrite laser, with patients also reporting less pain on the diode side. It was a small, single-centre proof-of-principle study, so the figures are encouraging but not conclusive.
Where the two technologies differ more clearly is in day-to-day ownership. A flashlamp is a consumable that degrades with use, and the crystal and optical path have to stay clean and aligned. Diode stacks generally last longer and need less maintenance, which shows up in running costs and downtime. Diode platforms also tend to be more compact and run at higher repetition rates, which shortens treatment times on backs and legs. Spot size varies more by model than by source, so compare it device by device.
Crystal lasers, for their part, have decades of published data behind them and deliver high energy per pulse through a round spot. Cooling differs as well, with crystal systems commonly using cryogen spray or cold air, while diode systems more often rely on contact cooling through a sapphire window.
Which suits you depends on your patient mix and how full your appointment book is. For more on the physics behind the two source types, read Diode Lasers vs Solid-State Lasers.
AlexStar as a Worked Example
The AlexStar Red Edition shows how diode delivery works in practice. It delivers the classic alexandrite wavelength band at 760nm through its PowerLine ALX handpiece, from a high-power diode source with a homogeneous 3cm² spot and pulses as short as 3ms.
It then adds the Nd:YAG band at 1060nm through the PowerLine YAG handpiece, giving practitioners a wavelength that penetrates more deeply and is better suited to darker skin types on the same system. Both wavelengths come from the same diode architecture, with 360° sapphire contact cooling and a dual-handpiece port for switching mid-session.
The AlexStar is a diode platform that delivers alexandrite and Nd:YAG wavelengths. It isn’t a crystal laser, so there’s no flashlamp to replace or crystal to maintain.
Comparing 755nm, 810nm and 1064nm
| Alexandrite band (755 to 760nm) | Classic diode band (810nm) | Nd:YAG band (1060 to 1064nm) | |
|---|---|---|---|
| Melanin absorption | Highest | Moderate | Lowest |
| Penetration depth | Shallower | Medium | Deepest |
| Best-suited skin types | I to IV | I to V | IV to VI |
| Best-suited hair | Fine and lighter | Most hair types | Coarse, deeper follicles |
| Asclepion platform | AlexStar (ALX handpiece) | MeDioStar | AlexStar (YAG handpiece) |
Most UK clinics don’t treat a single skin type. A busy clinic in Manchester, Birmingham or London might treat clients ranging from very fair to deeply pigmented skin within a single afternoon. A single-wavelength platform forces a compromise for part of that client base, either lower settings on darker skin or reduced efficiency on fine, light hair.
On a dual-wavelength platform, the practitioner can switch to 1060nm for a type V client and back to 760nm for the next client’s fine, fair hair without changing machines.
Our guide to Nd:YAG laser technology explains why 1064nm is the established choice for darker skin, and the MeDioStar pairs 810nm with 940nm for clinics that want one diode workhorse across skin types I to VI. Our laser hair removal devices page sets the two platforms side by side.
Other Applications of 755nm
Hair removal is the main use for long-pulsed 755nm, but the wavelength’s strong melanin absorption makes it useful elsewhere. Long-pulsed alexandrite lasers are used on benign pigmented lesions such as solar lentigines and freckles, and on some vascular targets, including leg veins in lighter skin.
Q-switched and picosecond 755nm lasers are established tools for pigment and tattoo removal. They’re particularly effective on green and blue inks, which absorb poorly at 1064nm and 532nm.
What to Consider Before Buying an Alexandrite Laser
Start with your clinic’s Fitzpatrick mix. If most of your clients are types I to III, an alexandrite-band platform will cover the bulk of your hair removal work efficiently. If a meaningful share are types V and VI, look for a system that also offers 1064nm.
Throughput comes next, as spot size and repetition rate determine how long a full back or pair of legs takes. This shapes how many appointments you can book in a day. Cooling and comfort can affect course completion too. If sessions are consistently unpleasant, some clients simply won’t finish the course.
Ask about consumables and servicing in detail, such as what needs replacing, how often, at what cost and how quickly an engineer can reach you. Weigh dual-wavelength flexibility against your likely patient base over the next five years, not just today’s. Training and support matter too, since even a capable platform is of limited value if your team isn’t confident using it.
Who you buy from matters as much as what you buy. We’ve set out the reasons why you should buy direct from the manufacturer and why regulatory certifications matter.
The Asclepion Academy provides device training for practitioners at every level. If you’re comparing hair removal platforms, you can also see how the MeDioStar compares with the Alma Soprano.
Laser Safety and Licensing in the UK
Hair removal lasers are Class 4 devices. Clinics need written local rules and a named Laser Protection Supervisor, plus an arrangement with a certified Laser Protection Adviser, in line with MHRA guidance. Many London boroughs also require a special treatment licence. Outside England, clinics using Class 3B or 4 lasers generally register with the national regulator: Healthcare Inspectorate Wales, the RQIA in Northern Ireland, or Healthcare Improvement Scotland where the service runs as an independent clinic.
England’s national licensing scheme for non-surgical cosmetic procedures isn’t in force yet. The 2023 government consultation proposed placing non-ablative laser hair removal in the green (lower-risk) tier, with most other non-ablative laser procedures in amber (medium risk). The government confirmed the three-tier model in August 2025, but the details may still change, so check the latest position before planning around it.
Alexandrite Laser FAQs
Is the AlexStar an alexandrite laser?
Not in the crystal sense. The AlexStar is a high-power diode platform that delivers the alexandrite wavelength band at 760nm through its PowerLine ALX handpiece and the Nd:YAG band at 1060nm through its PowerLine YAG handpiece. It gives you the clinical wavelength of an alexandrite laser without a flashlamp or crystal to maintain.
Is an alexandrite laser safe for darker skin?
The 755nm wavelength is well absorbed by epidermal melanin, so it carries a higher risk of burns and pigment change in darker skin. It’s generally used on Fitzpatrick types I to IV, with care at type IV. For types V and VI, the 1060 to 1064nm Nd:YAG band is the established choice because it penetrates deeper and is absorbed less at the surface.
Is alexandrite or diode better for hair removal?
Neither is better across the board. Comparative studies have found similar hair reduction between alexandrite and diode lasers, including 755nm diodes tested head to head against crystal alexandrite lasers. The real differences lie in skin-type range, treatment speed, cooling and running costs, so the better choice is whichever fits your patient base.
How many sessions does alexandrite laser hair removal take?
Most patients need a course of six to eight sessions spaced four to eight weeks apart, depending on the body area, followed by occasional maintenance treatments. Hair colour, thickness, skin type and hormonal factors all affect response, so the exact course differs from person to person.
What else can an alexandrite laser treat besides hair?
Long-pulsed 755nm lasers are used on benign pigmented lesions and some vascular lesions. Q-switched and picosecond 755nm lasers treat pigmentation and tattoos, and they’re particularly useful for green and blue inks.
How much does an alexandrite laser machine cost?
Pricing depends on the platform, the handpieces you choose and the training, warranty and service package that comes with it. Book a demo or request a quote and our team will put together a cost based on your clinic’s requirements.
See the AlexStar in Action
If you’re comparing alexandrite-band systems, a live demo lets you assess the handpieces, treatment speed, cooling and running costs directly. Book an AlexStar demo and our team will take you through the PowerLine ALX and YAG handpieces. You can also ask us about the A-List package when you do.
PicoSure® is a registered trademark of Cynosure. PicoWay® is a registered trademark of Candela. Soprano® is a registered trademark of Alma Lasers. Competitor details are drawn from published manufacturer materials.
