Carat Weight

measuring carat size using hands and finger

When it comes to buying an engagement ring, carat weight is often viewed as the most important criteria in selecting a diamond.

But, what does a 1 carat diamond really mean when you hear people saying it to describe a ring? Does a diamond with a bigger carat weight always appear larger?

Well, you find answers to these questions and more in this section of

Technically speaking, one carat is equal to 200 milligrams or 100 points. If you purchased a 1 carat stone, it means that you had bought yourself exactly 0.2 grams of diamond.

Also, many people have the misconception that a diamond with bigger carat weight will always appear larger. The truth is far from that. I’ll explain this by using real-life examples on a later page.

A Brief History of the Carat Weight And Its Origins

Before we continue, I want you to check out this short video to give you a quick overview of what carat weight is and how it is measured in the lab.



Now, if you are like many others, you might be wondering why a diamond’s weight is measured in terms of carats. Isn’t the use of SI units like the kilogram or its derivatives better suited to describe the weight of something so expensive?

Why not the use of ounces; which is a unit of measurement we are familiar with from everyday applications?

Well, the history behind this is pretty interesting. The word carat actually originates from carob; which refers to a locust tree that produces edible pods. Carob seeds, being even in weight, were used as weighing references by traders in the olden days.

carob seeds used for measurements

Without electronic balances, seeds were used as measurements

Remember, this was a time when high tech weighing machines were non-existent. Back then, one carat was equal to the weight of one carob seed and trades were made based on this simple estimation.

As you could have imagined, carob seeds varied in sizes and everybody was using different references depending on which part of the world you are in. Back in the 1890s, if you bought a “one-carat” diamond, the weight could actually vary anywhere between 0.94 to 1.06 metric carats!

That’s a huge amount of uncertainty considering the big sums of money paid for a single stone.

Much has changed since ancient times. While highly sensitive electronic weighing equipment has replaced the carob seeds, the industry stuck with the terminology of using carats to describe the weight of a diamond.

You do NOT need to learn how to use a loupe or be a gemologist in order to inspect a diamond in full details. Vendors like James Allen and White Flash allow you to interact with actual diamonds using 360° videos and experience online shopping like never before.

Why Is Diamond Carat Weight Perceived as the Most Important Factor?

suite of 3 different rings

How big is big enough? Where do we draw the line?

I’m sure you guys are familiar with this scenario. What’s the first reaction or question that comes to your mind when you hear about a new diamond jewelry purchase?

Without a doubt, questions associated with “What’s the carat size/weight of the diamond?” would instantly come to mind. The reason behind this is that the size of a diamond corresponds directly to the value and worth of the piece of jewelry.

And in many societies, it is an indication of a person’s status and wealth. On top of that, most of us have also been conditioned by the mass media and advertising campaigns into believing that bigger is always better.

Ads with catchy bylines like “Make your lady fall in love with a 1 carat diamond”, “Love is as big as it gets” etc… are all smart marketing tactics that jewelry companies employ to create a desire for bigger rings.

In fact, cliché movie lines like “If you loved me, you would have bought me a bigger diamond” had been so overused that the underlying meaning had been mentally etched in the minds of most people.

1 Important Thing You Need to Know About Carat Size

The truth is that jewelers know diamonds sell for more when they go pass certain sizes. It is no coincidence that the majority of diamonds in the market are cut to retain as much rough weight as possible at the expense of brilliance and beauty.

How often have you seen stones that weigh 0.48 or 0.98 carats? By design, such stones are rare oddities because they fall below the “magic sizes” that can fetch more money.

Instead, what you would observe is that the bulk of the stones would usually be cut to nice figures like 0.50 or 1.00 carats. Most of the time, this is done by compromising cut quality as the cutters strive to keep as much rough as possible.

With that said, don’t get carried away with choosing the biggest stone that you can find. This is one of the most common and yet, gravest mistakes that many first-time buyers make. What precedes a focus on the carat size of a diamond should be a consideration of other factors like cut, color and clarity as well.

We will be covering the different aspects with indepth details and examples over the next few pages.

Coming up, you can use the following carat size chart diagrams and tables to help visualize the physical size of a diamond. These charts are really helpful if you are new to diamond shopping and want to gauge the exact dimensions with respect to a corresponding weight.

Next Page >>

Related Articles

Share This Page on Social Media!


  1. Ryan-
    July 27, 2015 at 12:07 pm

    Do you have any tips on calculating diamond weight in carats or estimating how heavy it is based on dimensions? I’m considering to buy an antique ring that doesn’t have any certificate. The problem here is that the owner herself doesn’t know full details as well. If you could shed some advice, it would really be appreciated.

  2. Paul Gian-
    July 29, 2015 at 7:13 pm

    Unfortunately, there’s no easy way to do it accurately if the stone is mounted. The estimated weight would be within a range and would at best be an educated guess. You probably need to consult an appraiser where they can use professional tools to measure the stone. They will also have the necessary knowledge to calculate and provide a fairly accurate weight estimate.

    The more important issue I want to highlight is that you are buying an uncertified diamond. You won’t know for sure what you will be getting and you are subjecting yourself to unnecessary risks. My advice is: stay away.

    If you are looking for a vintage diamond ring, this page will probably interest you:

  3. Michael Guilas-
    June 12, 2016 at 8:27 am

    The gentleman is asking how to know the diamond well enough because he want to purchase the vintage ring. My concern is why are you discouraging him not to buy the ring that he want? What I can see here is you are using diamond learning website to get a customer for yourself. Please post your comment.

  4. Paul Gian-
    June 12, 2016 at 3:15 pm

    This website is specifically to help consumers make smart decisions and stay away from unethical vendors/scammy deals. Would you buy a vintage ring yourself without knowing FULL details? I won’t because the finer details do matter and affect the value of the ring. The solution is to take the ring to an independent appraiser or better yet, simply look for another vendor who can offer all the required information in the first place.

Leave A Comment