The short answer
The three main hair-removal lasers differ by wavelength: alexandrite (~755 nm) suits fair skin with dark hair, diode (~800–810 nm) is a versatile all-rounder, and Nd:YAG (~1064 nm) is the safest for darker skin. A longer wavelength reaches deeper and is absorbed less by skin pigment, which is why Nd:YAG is preferred for darker tones. None of them work well on blonde, red, grey or white hair. A practitioner matches the device to your skin and hair at consultation.
If you have read that there are different ‘types’ of laser, these three are the names you will actually meet: alexandrite, diode and Nd:YAG. They are not competing brands so much as different tools for different jobs, each defined by its wavelength. This page compares them directly — what each is good at, who each suits, and why the right one for you comes down to your skin tone and hair colour.
The three lasers at a glance
- Alexandrite ~755 nm — fair skin, dark hair
- Diode ~800–810 nm — versatile all-rounder
- Nd:YAG ~1064 nm — safest for darker skin
- Rule of thumb Longer wavelength → safer on dark skin
- Shared limit Poor on blonde, red, grey or white hair
- Chosen by Practitioner, at consultation
It all comes down to wavelength
These three lasers do the same fundamental job — heating the pigment in the follicle, as explained in how lasers target hair — but they do it with different wavelengths of light. Wavelength, measured in nanometres, decides two things: how deep the light reaches, and how much of it is absorbed by the pigment in the skin’s surface rather than the hair. A shorter wavelength is absorbed strongly near the surface; a longer one penetrates deeper and bypasses more surface pigment. That single property sorts these three into their roles.
The three lasers side by side
| Laser | Wavelength | Best for | Strengths | Watch-outs |
|---|---|---|---|---|
| Alexandrite | ~755 nm | Fair skin, dark hair | Fast, efficient on light skin | Higher risk on darker skin |
| Diode | ~800–810 nm | A broad range of tones | Versatile, widely available | Jack-of-all-trades rather than specialist |
| Nd:YAG | ~1064 nm | Darker skin tones | Safest on dark skin; deep reach | Can be less comfortable; needs skill |
When each is the right choice
- Alexandrite — its shorter wavelength is absorbed efficiently by hair pigment, making it fast and effective on fair skin with dark hair, but it is less suitable for darker skin because surface pigment absorbs too much of the light.
- Diode — a middle wavelength that balances penetration and absorption, which makes it a practical all-rounder used across many skin tones and the most common workhorse in UK clinics.
- Nd:YAG — the longest wavelength reaches deeper and is absorbed least by surface pigment, so it is the go-to for darker skin tones, as our page on different skin tones explains.
Some clinics own more than one device, or a single platform offering multiple wavelengths, so the practitioner can pick the best match for each person and even each body area.
Does the wavelength change the number of sessions?
A common question is whether choosing one laser over another means fewer appointments. In practice the device mainly affects safety and efficiency for your particular skin and hair, not the basic structure of a course. Whichever wavelength is used, the laser can only damage follicles that are in their active growth phase, so a course of several spaced sessions is still required — typically six to eight, sometimes more. What the right device does is make each session as effective and as safe as possible for you: an alexandrite laser working efficiently on fair skin, or an Nd:YAG working safely on darker skin, will both still need the full course to catch successive batches of growing hair.
- Same growth-cycle rule — all three only affect anagen-phase hair, so all need repeat sessions.
- Comfort can differ — some people find the longer-wavelength Nd:YAG less comfortable, which a practitioner can manage.
- Matching matters more than ‘best’ — the device suited to your skin will outperform a ‘better’ device used on the wrong skin.
What they all have in common
For all their differences, the three lasers share the same limits. None work well on blonde, red, grey or white hair, because there is too little pigment for any wavelength to target — see does laser hair removal work. All require a course of sessions, because each only affects hair in its growth phase. And all deliver long-term reduction rather than guaranteed permanence, as covered in is laser hair removal permanent. The choice between diode, alexandrite and Nd:YAG is about matching the device to your skin and hair safely — a decision for a qualified practitioner at a consultation, confirmed with a patch test.
Which of these lasers is right for you?
The best device depends on your skin tone and hair colour, and only a qualified practitioner can confirm it after a patch test. Find a regulated clinic to assess your options.
Frequently asked questions
Which laser is best, diode, alexandrite or Nd:YAG?
None is best overall — it depends on your skin and hair. Alexandrite suits fair skin with dark hair, Nd:YAG is safest for darker skin, and diode is a versatile middle option. A practitioner matches the device to you.
Why is Nd:YAG used for darker skin?
Its long 1064 nm wavelength penetrates deeper and is absorbed less by the skin’s surface pigment, so more energy reaches the follicle and less heats the skin. This makes it the safer choice for darker tones.
Is a diode laser good for all skin types?
The diode is a versatile all-rounder used across a broad range of skin tones, which is why it is so common in clinics. Even so, very dark skin is often best treated with Nd:YAG, and a patch test confirms suitability.
Do these lasers work on light-coloured hair?
No. None of the three work well on blonde, red, grey or white hair because there is too little pigment for any wavelength to target. Electrolysis may be a better option for those colours.
Sources & further reading
- NHS — Cosmetic procedures: laser hair removal and IPL
- MHRA — Lasers, intense light sources (IPL) and LEDs: guidance
- British Medical Laser Association (BMLA) — Laser device and wavelength information
- Joint Council for Cosmetic Practitioners (JCCP) — Choosing a practitioner and device
This guide is general information, not medical advice. A patch test and consultation with a qualified, regulated practitioner are essential before treatment, and results vary by individual. Laser achieves long-term hair reduction, not guaranteed permanent removal of every hair. Discuss any skin or health concerns with the practitioner or your GP.