Does a Diamond Shine or Glow? A Late-Night Debate Over Drinks

I still remember the first time I saw a diamond up close. It wasn’t in some fancy jewelry store or on a red carpet—it was at my cousin’s engagement party. She had just said yes, and suddenly, everyone was huddled around her hand, admiring the rock. "Wow, it's shining so brightly!" someone said. But then her fiancé, an engineer type, smirked. "Technically, it doesn’t shine. It reflects and refracts light."

That was the first time I heard someone challenge the idea that diamonds "shine." And honestly? It kind of ruined the magic for a second. But later that night, as we sat around a table with our drinks, we started debating—does a diamond shine, or does it glow?

The Science Behind a Diamond’s Sparkle

To really get into this, you have to understand how light interacts with a diamond. And trust me, I’m no scientist, but after that night, I did my research (and maybe got a little obsessed).

A diamond’s sparkle—what we often mistake for "shining"—is due to its ability to refract and reflect light. Light enters the diamond, bends (refraction), bounces around inside due to its precise cut, and then exits in a way that makes it look like it’s shimmering.

There’s even a technical term for this: brilliance. That’s the white light bouncing around inside, giving it that intense shimmer. Then there’s fire, which is when the light splits into colors, creating that rainbow-like effect. And finally, there’s scintillation, which is the sparkle you see when you move the diamond around.

So, diamonds don’t shine by themselves. They don’t emit light like a glow-in-the-dark toy. They react to light, making them look like they’re shining.

But Can Diamonds Glow?

"Okay, but what about those diamonds that glow in the dark?" my friend Chris chimed in that night.

Good question. Some diamonds actually do glow under UV light. This is called fluorescence, and about 30% to 35% of diamonds exhibit this phenomenon. It happens because of tiny impurities in the stone, usually boron, that cause it to absorb UV light and then emit a bluish glow.

I once saw this in person at a jewelry store. The jeweler put a diamond under a UV lamp, and suddenly, it was glowing blue, almost like a nightclub light. It was wild to see something that looked so "normal" in daylight suddenly transform under UV. Some diamonds even glow in shades of green, yellow, or white.

But here’s the thing—this glow is only visible under UV light. Once you turn the light off, the glow disappears. It’s not like those glow-in-the-dark stars you stick on your ceiling as a kid.

The Debate Continues

"Alright, so diamonds don’t actually shine, and they only glow under special light," my friend Alex concluded that night. "So why do people always say ‘shine bright like a diamond’?"

We all laughed, but it’s a fair point. Marketing and pop culture have made us think diamonds emit light on their own. Songs, commercials, even old-school Hollywood movies have reinforced this idea.

But if you ever hear someone say, "That diamond is shining," now you know—it’s not really shining. It’s just bending light in a way that makes it look magical.

So, What’s the Final Verdict?

If you ask a scientist, they’ll tell you diamonds don’t shine, they reflect and refract light. If you ask a jeweler, they’ll say some diamonds fluoresce under UV light. But if you ask my cousin? She’ll just smile and say, "Who cares? It’s beautiful."

And maybe that’s the real answer. Whether it shines, sparkles, or glows, a diamond is special because of how it makes people feel. Whether you’re proposing, celebrating, or just admiring one over drinks, that little rock has a way of capturing our attention—no matter how you define its light.

Is 165 cm normal for a 15 year old?

The predicted height for a female, based on your parents heights, is 155 to 165cm. Most 15 year old girls are nearly done growing. I was too. It's a very normal height for a girl.

Is 160 cm too tall for a 12 year old?

How Tall Should a 12 Year Old Be? We can only speak to national average heights here in North America, whereby, a 12 year old girl would be between 137 cm to 162 cm tall (4-1/2 to 5-1/3 feet). A 12 year old boy should be between 137 cm to 160 cm tall (4-1/2 to 5-1/4 feet).

How tall is a average 15 year old?

Average Height to Weight for Teenage Boys - 13 to 20 Years

How to get taller at 18?

Staying physically active is even more essential from childhood to grow and improve overall health. But taking it up even in adulthood can help you add a few inches to your height. Strength-building exercises, yoga, jumping rope, and biking all can help to increase your flexibility and grow a few inches taller.

Is 5.7 a good height for a 15 year old boy?

Generally speaking, the average height for 15 year olds girls is 62.9 inches (or 159.7 cm). On the other hand, teen boys at the age of 15 have a much higher average height, which is 67.0 inches (or 170.1 cm).

Can you grow between 16 and 18?

Most girls stop growing taller by age 14 or 15. However, after their early teenage growth spurt, boys continue gaining height at a gradual pace until around 18. Note that some kids will stop growing earlier and others may keep growing a year or two more.

Can you grow 1 cm after 17?

Even with a healthy diet, most people's height won't increase after age 18 to 20. The graph below shows the rate of growth from birth to age 20. As you can see, the growth lines fall to zero between ages 18 and 20 ( 7 , 8 ). The reason why your height stops increasing is your bones, specifically your growth plates.