Please check this first before reading

Q. Aren’t the two devices basically similar?

A. The wavelengths are different: 755nm and 1064nm.

The penetration depth and the kinds of hair they target are different too.

Q. Then why, if both are hair removal, do the results differ?

A. Because the right wavelength varies depending on hair thickness, depth, and skin tone.

If you use only one device, you’ll end up at a disadvantage in some areas.

Alexandrite and Nd:YAG look similar, right? But actually, they’re not

Alexandrite is a laser that uses the 755nm wavelength,

and because it has a high melanin absorption rate,

it’s a strong device for targeting shallow, fine hairs.

Nd:YAG uses the 1064nm wavelength,

and reaches deeper layers of the skin,

so it’s effective for thick, deeply rooted hairs.

They’re grouped together as the same ‘laser hair removal,’

but unlike Alexandrite,

Nd:YAG has a lower melanin absorption rate,

which means it can be used safely even on darker skin tones.

Simply put,

these are two devices with completely different targets.

Alexandrite vs Nd:YAG: why is it that it’s hair removal for both, but some people see results and others don’t?

Director Wi Young-jin’s key insight

755nm Alexandrite is strong for shallow, fine hairs,

while 1064nm Nd:YAG is strong for thick, deep hairs. Clinics that choose wavelengths by area instead of using only one device get better results.

Most people who search for Alexandrite vs Nd:YAG and come in

are usually dealing with something like

"I tried it once and it wasn’t that great"

"The results are way different from area to area"

that kind of concern.

But in many cases, it’s not a problem with your follicles—

it’s quite likely that the wavelength just wasn’t a good match.

The depth of the hair roots varies by body area.

Thicker underarm and leg hair

can go 4–5mm below the skin surface,

while facial peach fuzz or fine arm hair

is only about 1–2mm deep.

755nm Alexandrite

is well absorbed by melanin,

but its penetration depth is relatively shallow,

whereas 1064nm Nd:YAG

has lower absorption but goes deeper.

So for shallow, fine hairs on the face or arms,

Alexandrite is more efficient,

and for thick, deep hairs like underarms, bikini area, or men’s beards,

Nd:YAG is much more advantageous.

That may not really sink in just by reading, but it becomes clear when you look at actual cases.

Last month, a 26-year-old man came in,

and he said he had gotten beard hair removal

8 times elsewhere with only minimal results,

so he said, “I’m not expecting much this time either.”

Looking at his chart,

every treatment he had received was with a single Alexandrite device.

Men’s beard roots are deeper than 4mm,

and with 755nm, the energy

simply doesn’t reach that far enough.

We switched the wavelength to Nd:YAG

and did two sessions,

and he was the one who said, “I’ve never seen it shed this fast.”

He was more surprised than anyone.

But that doesn’t mean Nd:YAG is always better.

The same man also had treatment for arm hair,

and that area was captured much better with Alexandrite.

In the end, even within one person,

switching wavelengths by area

is the most reasonable approach.

Director Wi Young-jin’s key takeaway

755nm is for shallow, fine hairs; 1064nm is for thick, deep hairs.

Compared with a clinic that runs only one device, a clinic that selects between the two wavelengths by area

gets better results for the same number of sessions.

Alexandrite vs Nd:YAG: take a look and see which one applies to you

If you look at it this way, the difference should be clear.

To sum it up:

If you mainly have fine hair and a light skin tone,

Alexandrite alone is enough.

If your skin tone is darker or you tan often,

or if you need to target thick, deep hairs like men’s beard, underarms, or bikini area,

Nd:YAG is the right choice.

The most ideal approach is

to switch wavelengths within the same session,

using Alexandrite for the face,

and Nd:YAG for the body,

separately.

If you’ve read this far, this is probably what you’re wondering

Q1. Which clinics use both wavelengths?

This is a bit awkward to ask,

(because sometimes the staff doesn’t know)

(which means they don’t use 1064)

When people inquire,

we tell them that we switch wavelengths back and forth depending on the condition—something like that

Q2. About how many sessions does it usually take to see results?

I used to think the number of sessions was pretty much the same, too.

But it varies by person and by clinic.

Thick hair, clinic doesn’t pay attention > 20 sessions

Normal hair, clinic pays attention to energy > 6 sessions

When people use Alexandrite for facial peach fuzz,

it’s usually cleaned up in about 5–6 sessions,

but when using Nd:YAG for men’s beards,

you should expect 8–10 sessions.

Because of the hair growth cycle, 4–6 week intervals are the standard,

and continuing without missing sessions

makes a difference in results.

This is the last question I get most often.

Q3. Which one has a greater risk of side effects or burns?

This is something I explain the same way every time I see patients,

but more important than the wavelength itself

is blindly cranking up the energy,

which is the most dangerous thing.

Especially on darker skin tones,

if you hit hard with 755nm,

the risk of burns and pigmentation increases.

For those people,

starting with 1064nm Nd:YAG

is much safer.

A place that looks at your skin tone and hair depth

and adjusts the wavelength and energy together

is what ultimately reduces side effects too.

If you take away just one thing today — rather than a place that does everything with a single device,


look for a clinic that switches wavelengths by area.



In the next post, I’ll break down “laser hair removal session intervals: how to choose between 4 weeks and 6 weeks.”


I’ll show with cases why the shedding speed changes depending on how you space treatments, even for the same area.


This was Wi Young-jin.

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