I’m about to propose to my girlfriend, and I’d like to declare my love with a gem that causes the least damage possible to the planet. How do I go about doing that?

In recent years, consumers have learned to be wary about the political issues involved with gemstones—like the “blood diamonds” that financed wars in Sierra Leone, Angola, and the Democratic Republic of Congo or the rubies that support the military junta in Burma. But jewels have environmental impacts as well as social ones, and ethical consumers should consider both when buying their bling.

There are two types of gem-mining operations: large industrial mines and small-scale, informal digging sites. Most of the world’s diamonds come from the former, while the vast majority of colored gemstones—like rubies, sapphires, and emeralds—come from the latter.

Big mines can have correspondingly big impacts. They disturb wide swathes of land and sometimes affect biodiversity in drastic ways. They mayuse a lot of water for processing the gems, and the huge amounts of waste rock they produce can contribute to acid rock drainage . (The average diamond in an engagement ring requires the removal of 200 million to 400 million times its volume in rock.) Meanwhile, the machines used to dig diamonds out of kimberlite orecan have hefty carbon footprints.

Small-scale mines, on the other hand, have the potential to be relatively low-impact, since the process is so much simpler. But when they’re poorly run, these small mines can cause great damage, particularly if they’re located in ecologically sensitive areas. Washing gems in nearby rivers or streams can pollute those waterways with silt and sediment, altering aquatic habitats. When laborers flock to a site where gems have been found, forests are often cleared to create more digging sites. Trees also come down for the sake of cooking fires, and hunting can decimate local wildlife populations. Improper use of machinery can lead to oil spills and excess greenhouse-gas emissions.

It’s relatively easy to mitigate these consequences—if you can provide the miners with adequate training and organizational support. But that’s a tall order, since thousands of such sites are scattered throughout the developing world, where environmental regulations are often laxer to begin with. Big mines, run by big corporations, are much easier to monitor and hold accountable for their records on both environmental and human-rights issues.

In an ideal world, your ring’s mine-to-market journey would be tracked by an independent organization that verified which sustainability measures were in place at each step. That’s not the case, unfortunately. The fine jewelry industry is pushing toward greater transparency and accountability, but it will be some time before consumers can reliably get robust, credible information on the provenance of their baubles, particularly colored gemstones.

If you really want to start your marriage with a clean slate, consider an old ring—antique jewelry is the greenest, safest option. If you don’t have a grandma with an heirloom gem, there are plenty of places where you can find high-quality, new-to-you rings. A fashion editor friend of the Lantern’s—who is herself getting married with a vintage band—recommends the wares at Erie Basin and Doyle & Doyle. (These two stores are based in New York, but they have e-commerce outlets.)

You should also consider synthetic gemstones. These days, it’s possible to grow rocks that have the same physical, chemical, and optical characteristics as their natural counterparts—even trained gemologists often can’t tell the difference. (Their makers like to call them “grown” or “cultured” stones, to capture some of that alluring sense of terroir.) These “synthetics” are distinguished from “simulants,” like glass or cubic zirconium, which merely imitate the appearance of precious gems. Mining is still required to produce the raw materials for synthetic stones, such as alumina for rubies or graphite for diamonds. But Saleem Ali, a professor who has studied the social and environmental impacts of gem mining, notes that those materials are already being mined in large quantities for other applications. So the relatively tiny demand for synthetic jewels isn’t driving mining activity the way it drives mining for natural gems.

It takes some energy to fabricate those flashy rocks, but the total amount used may be comparable across synthetic and natural gemstone operations—at least when it comes to diamonds. Ali has collected diamond mine energy-use figures ranging from 7.5 kilowatt-hours per carat at the Argyle mine in Western Australia to an average of 80.3 kWh per carat across De Beers’ various operations. (That includes washing and processing the stones.) Meanwhile, producers of synthetics quoted figures to the Lantern ranging from 20 kWh to 80 kWh to grow one carat of diamond in a lab. Those data points don’t tell the whole picture: In both cases, you need to consider the energy costs of transporting the gems, and with synthetic stones you need to add in the extraction of the raw materials. At the very least, though, the energy that goes into synthesizing a diamond doesn’t seem like an environmental deal-breaker. (A bigger issue for the Lantern would be where the gem was cut and polished, since there are child-labor and worker-safety issues associated with that process, particularly on the lower end of the market.)

If your beloved must have a new and natural stone, you’re just going to have to deal with the information gap. The best thing you can do is seek out jewelers who have stated their commitment to buy gems from sustainable sources. Many such companies are involved in the cross-sector working group known as the Madison Dialogue; its list of participants would be a good place to start looking for ring-shopping options. (Check out, for example, the work being done by Columbia Gem House.) The Web site Fairjewelry.org also maintains a list of ethically minded companies. Several experts the Lantern spoke with also had praise for the efforts being made at Wal-Mart and Tiffany’s. However, without an independent organization certifying a jeweler’s sustainability claims, you’re going to have to decide for yourself whether you trust the company’s marketing department.

Is there an environmental quandary that’s been keeping you up at night? Send it to ask.the.lantern@gmail.com, and check this space every Tuesday.

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