The “0.70 ct” Trick: Why Salespeople Love It (and When You Should Too)

Intro: You’ve probably seen a diamond labeled “0.70 ct” and felt like it sounded almost like 3/4 of a carat but somehow cheaper. That feeling is not an accident. Salespeople use weights like 0.70 carat because they sit just below price thresholds where diamonds jump in cost. Knowing why this works helps you decide when a 0.70 ct stone is a smart buy and when it’s a marketing move you should avoid.

Here’s the basic idea: diamond pricing is not linear. Retail and wholesale markets treat certain weights as milestones — 0.50 ct, 0.75 ct, 1.00 ct are common examples. At those milestones the price per carat rises sharply. A stone that is 0.75 ct or 1.00 ct often carries a premium because buyers perceive it as a “milestone” size. A 0.70 ct stone looks almost the same to the eye as a 0.75 ct, but it often costs noticeably less. That gap is where the salesperson’s “trick” lives.

Why price jumps happen

• Buyer psychology: People anchor to round numbers. One carat is memorable and desirable. Retailers know that and price accordingly.
• Supply and demand: Gem cutters produce certain target sizes more than others. Availability and demand change the wholesale curve, creating price breaks between targets.
• Per-carat math: Diamond prices are quoted per carat. As you cross a milestone, that per-carat figure multiplies by a larger weight and inflates total price.

How big is a 0.70 ct stone, actually?

Carat measures weight, not diameter. For a round brilliant, a 0.70 ct diamond will typically face up about 5.7–5.9 mm in diameter. A 0.75 ct might be roughly 5.8–6.0 mm, and a 1.00 ct is about 6.4–6.5 mm. That means the visible size difference between 0.70 and 0.75 is tiny—often invisible to the untrained eye—while the price difference can be significant.

Typical savings and trade-offs

Exact numbers vary by market, time, and the stone’s color/clarity/cut. But in practice:

• A 0.70 ct stone can cost 10–30% less than a comparable-quality 0.75 ct stone.
• That saving often lets you move up a grade in cut, color, or clarity while keeping the same budget. Cut quality matters most for sparkle; small sacrifices in carat weight can give much bigger gains in brilliance.
• The downside is perceived value. If the buyer (or their circle) cares about hitting a milestone like 3/4 ct or 1.00 ct, a 0.70 won’t carry the same prestige even if it looks the same.

When a 0.70 ct is a good choice

• You want the best sparkle for your budget: If you can trade 0.05 ct for a jump from “Good” cut to “Very Good” or “Excellent,” do it. Visible brilliance beats tiny weight differences.
• Face-up size is similar: If the diameter (mm) is nearly the same as a higher-weight stone, choose the better-cut 0.70. Focus on spread—how large it looks—rather than carat alone.
• Resale isn’t your concern: If you plan to wear the ring and not resell soon, subjective milestones matter less than everyday beauty and durability.

When you should avoid the 0.70 tactic

• You want an exact milestone: If symbolic weight matters—1.00 ct, 0.75 ct, or a known size for cultural reasons—don’t pick 0.70 to save money. The value and sentiment tied to the milestone matter.
• You’re buying ungraded or uncertified stones: Without a lab report you can’t verify the exact weight or quality. A listed “0.70 ct” without a certificate could be misleading.
• You need predictable resale value: Stones at recognized breaking points can hold value better if you plan to sell or trade up later.

Practical steps to decide on a 0.70 diamond

• Ask to see the lab report: Look for the exact carat weight, dimensions in mm, and cut grade. GIA, AGS, and similar labs give reliable data.
• Compare diameter, not just carat: If a 0.70 ct has a diameter within ~0.1 mm of a 0.75 ct, the face-up size is essentially the same.
• Check cut, polish, and symmetry: A better cut will reflect more light. A 0.70 with Excellent cut will appear brighter than a poorly cut 0.75.
• Price-per-carat math: Ask for both price per carat and total price. Compare the effective cost rather than relying on the label alone.
• Consider fluorescence and depth: Heavy fluorescence or deep cut can reduce brilliance. Ensure the stone’s proportions are in a good range for its cut.
• Ask about return/upgrading policy: If you later decide you want the milestone size, check whether the retailer offers trade-ins or upgrades.

Quick questions to ask a salesperson

• “Can I see the laboratory certificate?”
• “What are the exact dimensions in mm and the depth/table percentages?”
• “What is the price per carat and the total price?”
• “How does the face-up diameter compare with a 0.75 ct / 1.00 ct of the same cut?”
• “What’s your return or upgrade policy if I want a larger stone later?”

Bottom line

“0.70 ct” is a useful tactic because it sits just below weight thresholds that command higher prices. That makes it a smart choice when you want the most sparkle and value for your money. But it’s not always the right call. If hitting a milestone matters to you, or if you need a certified, resale-friendly stone, choose accordingly. Focus on mm, cut quality, and the lab report. Those things determine how the diamond actually looks and performs—far more than the two decimal places on the carat weight.