On November 16, 2010, Prince William, heir to England’s royal throne, announced his engagement to Catherine Elizabeth Middleton. Prince William presented Kate Middleton with the same ring that his father, Prince Charles, gave to his mother, the late Princess Diana, at the time of their engagement in 1981: an 18-carat oval blue sapphire surrounded by fourteen brilliant cut diamonds set in 18-carat white gold, a Windsor family heirloom created by the official crown jeweler of the British Monarchy, Garrard Jewelers.

In the advent of the Royal wedding on April 29, 2011, commoners are anxious to purchase affordable replicas of the royal engagement ring. As Kate Middleton’s ring is one of the most coveted pieces of jewelry in the world, replicas are currently one of the top-selling engagement rings in both the United Kingdom and the United States.

Although Kate’s ring is valued at 225,000 British pounds, replicas are selling for as little as 9.99 US dollars. While a ring valued at this price is nothing more than a cheap knock-off, quality replicas of the royal engagement ring can be purchased for the same amount of money one would choose to spend on any legitimate engagement ring. How can a ring matching the beauty and uniqueness of the royal engagement ring be affordable for commoners? The secret lies in the combination of materials used and the ways in which the gemstones and metals are processed.

Sapphires: Most sapphires have dull colors and poor clarity when they are extracted from the earth, so they are usually treated in labs before becoming a bright, sparkling gemstone like the one in Kate Middleton’s ring. Sapphires that have this appearance without laboratory treatment are extremely rare and very expensive, accounting for only about 1% of sapphires that have been harvested to date.

Synthetic sapphires are considered to be real, genuine sapphires, but they have been created by humans in a lab rather than extracted from the earth. Sapphires that come from the earth are rare and very expensive, while synthetically produced ones are inexpensive to create in a lab, making sapphires a fairly common and affordable gemstone. Most sapphires for sale at an “affordable” price can be assumed to have been synthetically produced, and most jewelers will reveal a sapphire’s origins to potential buyers.

Imitation sapphires are most often made from blue glass, blue cubic zirconia, or synthetic spinel. Imitation sapphires often look too perfect or too clear, while a real one will come with slight imperfections that make it both unique and beautiful. Of course, the surefire way to tell an imitation sapphire is by the price, as in the cheap replicas of the royal engagement ring selling for $9.99.

While sapphires that came from the earth may be unaffordable to most, a synthetic sapphire is a perfectly appropriate and legitimate substitute that you’ll find for sale at a fair price from most jewelers.

Diamonds: The price of a half-carat diamond ranges anywhere from under $1000 to over $3000, depending on the color, cut, and quality of the gemstone. While a 1-carat diamond with a good cut can be found for around $5000, a ring like Kate Middleton’s containing fourteen of these diamonds could be quite costly, especially after adding in the price of the 18-carat sapphire and white gold.

Although diamonds are the most coveted and most expensive gemstone of our time, they are not particularly rare and may even be considered a renewable resource that will never be exhausted from the earth. Still, their high price is dictated by supply and demand, as well as by the four C’s of diamonds: cut, clarity, color, and carat (size).

Imitation diamonds are fairly common, and most often come in the form of cubic zirconia (cz). The look of cz is actually very similar to that of a real diamond, and professional testing equipment is usually required to distinguish between the two materials. Moissanite is another, less common type of imitation diamond, also difficult to distinguish from the real thing without testing equipment. While cz and moissanite will scratch more easily than a diamond, all three materials produce brilliant rainbows when held up to light.

Glass imitation diamonds, on the other hand, do not produce rainbows, and this is what is most often used to make cheap diamond knock-offs like the ones in the rings priced at $9.99. While cz is much more affordable than a real diamond, it is also not considered a cheap imitation and it’s use is fairly common in legitimate jewelry.

Purchasing Your Own Royal Engagement Ring: If you happen to be a “commoner,” as most of us are, don’t fret. You can still present your bride-to-be with her own royal engagement ring for a decent cost without stooping to the ultra-low price of $9.99. Talk to your jeweler about creating a custom engagement ring that integrates one or more of the elements discussed above. A lab-created sapphire surrounded by low-carat diamonds or larger cuts of cubic zirconia in a white gold setting will not be out of reach.