Preserving blood in a necklace requires keeping it liquid (or at least stable in appearance) inside a sealed glass vial, then protecting that vial from breakage, heat, and sunlight. The process is straightforward with the right materials, but skipping key steps leads to clotting, bacterial growth, and discoloration within days.
What You Need
The core components are a small glass vial, an anticoagulant to prevent clotting, a sealant, and a necklace setting or cage to hold the vial. Here’s a practical shopping list:
- Glass vial: A 1 ml borosilicate glass vial with a crimp or screw top. Borosilicate glass resists temperature changes and chemicals far better than standard craft glass. Look for Type I borosilicate vials with a 13 mm closure, widely available from lab supply retailers.
- Anticoagulant: EDTA (ethylenediaminetetraacetic acid) is the most reliable option. It works by binding the calcium ions in blood that trigger clotting. You can buy small EDTA blood collection tubes (often called “lavender top” tubes) from medical supply stores. These come pre-loaded with the correct ratio of EDTA for the tube’s volume.
- Sealant: Two-part epoxy or UV-cure resin to permanently seal the vial’s opening after filling.
- Necklace finding: A pendant cage, wire wrap, or bail that fits your vial size.
Collecting and Treating the Blood
You only need a few drops. The cleanest method is using a sterile lancet (the same type used for at-home blood sugar testing) on a clean fingertip. Wipe the finger with an alcohol swab first and let it dry completely before pricking, since alcohol in the sample can damage blood cells and change the color.
Collect the blood directly into a small EDTA tube or onto a clean surface where you can mix it with EDTA before transferring it to the vial. If you’re using a pre-loaded EDTA tube, gently invert it several times to mix. The EDTA needs contact with the blood immediately. Blood begins clotting within seconds of leaving the body, so don’t wait.
If you can’t find EDTA tubes, a tiny pinch of powdered EDTA (dipotassium or tripotassium salt, available from chemical suppliers) dissolved in a single drop of distilled water works. The standard ratio in lab tubes is about 1.8 mg of EDTA per milliliter of blood. For a 1 ml vial that’s mostly decorative and only partially filled, this amount is forgiving. Slightly more EDTA won’t hurt the appearance.
Why Anticoagulant Matters
Without an anticoagulant, blood clots into a dark, rubbery mass within minutes. EDTA keeps it in a liquid state by removing calcium from the clotting process. Heparin is another option (it works differently, by blocking the conversion of fibrinogen into fibrin), but EDTA is preferred for long-term storage because it’s more stable at room temperature and better at maintaining the blood’s visual consistency over months.
Some online tutorials suggest using a drop of saline or nothing at all. These approaches fail. Untreated blood will clot, separate into layers, and eventually become a brown sludge that looks nothing like fresh blood.
Filling and Sealing the Vial
Use a clean syringe (without a needle) or a disposable pipette to transfer the treated blood into the borosilicate vial. Fill it most of the way, leaving a small air bubble. A completely full vial with zero air space is more likely to crack with temperature changes because liquid expands slightly when warmed.
Sealing is the most important step for longevity. A cork or rubber stopper alone will eventually let air in, which causes oxidation and browning. After inserting the stopper, apply a layer of two-part epoxy or UV-cure resin over the top, covering the seal completely. Some people add a second coat after the first cures. The goal is an airtight, permanent closure. Any oxygen exchange accelerates the breakdown of hemoglobin (the molecule that gives blood its red color), turning the sample dark brown.
Color Changes Over Time
Even with perfect preservation, expect some color shift. Fresh blood is bright red due to oxygenated hemoglobin. Within the sealed vial, oxygen is limited, so the blood will gradually darken to a deep crimson or burgundy. This is normal and happens within the first few weeks.
UV light accelerates further changes. Research on blood samples exposed to ultraviolet light shows that higher UV exposure causes blood to shift from deep brownish-red to a lighter brown with a paler center. The differences are subtle when viewed in isolation, but side by side with a protected sample, the fading is visible. Keeping the necklace under clothing or away from prolonged direct sunlight slows this process significantly.
Heat is another factor. Store the necklace away from hot car dashboards, windowsills, and other places where temperatures spike. Heat accelerates both chemical degradation and bacterial activity if any contamination is present.
Preventing Bacterial Growth
Blood at room temperature is an excellent growth medium for bacteria. Skin bacteria like Staphylococcus epidermidis are the most common contaminants, introduced during collection. More concerning gram-negative bacteria such as Serratia or Salmonella species can cause serious illness if the vial breaks and contacts broken skin or mucous membranes.
EDTA alone does not sterilize blood. To reduce bacterial risk, some people add a tiny amount of sodium azide (a common lab preservative) to the sample. This is effective but highly toxic in larger quantities, so it carries its own risks. A safer approach for a decorative piece is to keep the volume small, ensure a completely airtight seal, and accept that the sample is not sterile. The sealed environment limits bacterial growth because oxygen runs out quickly in a tiny vial, and most skin bacteria need oxygen to thrive.
The most practical safety measure is a strong seal and durable glass. If the vial can’t break and can’t leak, contamination risk stays contained.
Assembling the Necklace
Once the vial is filled and sealed, attach it to a necklace chain using a bail, wire wrapping, or a premade pendant cage. Many jewelry suppliers sell small vial pendant settings specifically designed for 1 ml vials. Wire wrapping with craft wire (20 or 22 gauge) gives a secure hold and lets you customize the look.
If you’re concerned about breakage during daily wear, consider adding a thin layer of clear heat-shrink tubing or a silicone sleeve around the glass before mounting it. This won’t make it unbreakable, but it will contain the contents if the glass does crack.
Shipping and Legal Considerations
If you’re making these for others or ordering one from an artist, shipping rules apply. USPS classifies most small blood samples in sealed jewelry as nonregulated biological material, meaning they’re mailable as long as they don’t contain known infectious agents and are properly packaged. Nonregulated materials must follow specific packaging instructions (USPS Publication 52, Packaging Instruction 6G), which generally require leak-proof primary containers, absorbent material, and a rigid outer box.
Blood samples known or suspected to be infectious fall under Category B infectious substance rules, which limit shipments to 50 ml of liquid per package and require UN 3373 labeling. A healthy person’s blood in a 1 ml sealed vial typically qualifies as nonregulated, but if there’s any reason to suspect a bloodborne pathogen, stricter rules apply. Private carriers like FedEx and UPS have their own policies, and some refuse biological materials from non-institutional senders entirely.