Diamond Filament Bulb E27 40W Tungsten — 2700K Authentic Incandescent, Faceted Glass Body
A vintage incandescent bulb with a faceted diamond-shaped glass body and a classic straight tungsten filament, delivering a deep 2700K amber tone at 40W. E27 cap, standard EU/UK mains (220–240V). CE, RoHS and CCC certified. Bulb sold individually — fitting not included.
Technical Specifications
| Light source | Incandescent tungsten filament — replaceable |
| Cap / Socket | E27 (standard Edison screw) — also fits E26 |
| Bulb shape | Diamond — faceted geometric glass body |
| Filament type | Straight tungsten — classic Edison style |
| Wattage | 40W |
| Colour temperature | 2700K — extra warm amber |
| Voltage | 220–240V / 50Hz |
| Glass | Clear — faceted diamond body |
| Dimmable | Yes — compatible with standard incandescent dimmers |
| Certifications | CE (EU / UK), RoHS, CCC |
Diamond Tungsten — Geometric Precision, Prismatic Refraction, Authentic Glow
The diamond shape and the tungsten filament are two separate arguments for this bulb, and they work differently. The faceted glass body is a geometric statement — precise, angular, and visually distinct from the rounded profiles of most vintage bulbs. Each flat face of the diamond refracts the filament glow at a different angle, casting subtle prismatic reflections on surrounding surfaces that shift as you move around the fitting. The tungsten filament is the other argument: a single straight wire that glows at a colour temperature no LED can fully replicate — genuine 2700K amber, with the slight flicker and warmth that comes from a real incandescent source. Together, the two elements produce a bulb that is simultaneously a precision object and an authentic light source. At 40W, the output is noticeably brighter than the 4W LED version of the same shape — enough for a pendant over a dining table or a statement floor lamp, not just a bedside accent. It dims smoothly with a standard incandescent dimmer, and the colour temperature deepens further as the output drops.
This bulb is best used in open or clear-glass fittings where both the diamond silhouette and the straight filament are fully visible. The prismatic refraction effect is most pronounced in darker rooms and at lower dimmer settings. In a multi-bulb fitting, the faceted faces of adjacent diamond bulbs interact with each other’s light, creating a layered reflection pattern that a smooth globe cannot produce. Browse our pendant lights collection for compatible open fittings, or read our lamps guide for advice on pairing decorative bulbs with the right fitting.
Common Questions
What is the difference between this 40W tungsten version and the 4W LED diamond bulb?
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Both have the same faceted diamond glass body, but the light source differs significantly. This 40W version uses a real tungsten filament — a single straight wire that produces authentic incandescent light at 2700K, with the warmth, slight flicker, and colour rendering that only tungsten delivers. It is also noticeably brighter. The 4W LED version uses a spiral LED filament, consumes 90% less energy, and has a much longer lifespan, but the light quality is slightly different. Choose tungsten for authenticity and brightness; choose LED for efficiency and longevity.
Does the faceted glass get hot to the touch?
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Yes — as a 40W incandescent, this bulb generates significant heat during operation. The glass surface will become hot and should not be touched while the bulb is on or immediately after switching off. Ensure the fitting you use is rated for at least 40W and that there is adequate clearance around the bulb. Do not use in enclosed fittings that trap heat, and keep away from flammable materials.
Is the prismatic refraction effect visible in a well-lit room?
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The refraction effect is most visible in low-light conditions — in the evening, in a dimmed room, or when the bulb is the primary light source. In a brightly lit space with multiple light sources, the prismatic reflections are less noticeable but the diamond silhouette remains visually distinctive. For the full effect, use this bulb as the centrepiece of a fitting in a room where you can control the ambient light level.
Can I use this in a fitting rated for 25W or 40W maximum?
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Only if the fitting is rated for 40W or above. Using a 40W bulb in a fitting rated for 25W maximum creates a fire risk due to excess heat. Always check the maximum wattage rating on your fitting — it is usually printed on a label near the socket. If your fitting is rated for 25W, use the 4W LED version of this bulb instead, which produces far less heat and is safe in lower-rated fittings.
How long will a 40W tungsten bulb last compared to an LED?
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A standard 40W tungsten incandescent typically lasts 1 000–2 000 hours — roughly 9 months to 1.5 years at 4 hours of daily use. An LED equivalent in the same diamond shape is rated for 50 000 hours, or over 34 years at the same usage rate. The tungsten version requires more frequent replacement and consumes more energy, but delivers a light quality and authenticity that many people prefer for decorative applications. Factor in the replacement cost when comparing the two options.
Find compatible open fittings in our Pendant Lights or Floor Lamps collection. Free delivery on orders over €50. 30-day returns.
