We test out a mountaineering down jacket that offers superb warmth-to-weight performance... and at a great priceReviewSpecsGalleryRetailersLa Sportiva are one of the dominant mountain footwear brands in the UK, beloved of mountain professionals and weekend warriors alike, but you dont see as much of their clothing out on the hill as home-grown brands such as Rab, Berghaus and Mountain Equipment. That may well change though if they bring out more products such as this Lumina 300 down jacket an extremely high-spec piece that comes with a surprisingly low pricetag for what it is offering. Too good to be true? Lets find outThe SpecsThe specs of the Lumina 300 are really impressive the jacket contains 172g of 1000-fillpower down, with an overall weight of just 350g. The outer is made from Pertex Quantum with Diamond Fuse technology (53% Recycled Polyamide, 47% Polyamide), which is a very light and downproof material, but also pretty durable. The Diamond Fuse technology means that the yarns it uses have diamond-shaped filaments that lock together to create a durable and highly abrasion-resistant fabric. In our experience the fabric is quite resistant to scraping against rocks and ice, or pack straps rubbing against it; however, it (unsurprisingly) doesnt like sharp-edges such as crampon points or ice axe picks.The down filling of the Lumina 300 is extremely high qualityThe quality of the down inside the Lumina 300 is about as good as you can get, and La Sportiva go as far as to say the Lumina 300 has likely the best warmth-to-weight ratio in the world. Certainly what you immediately notice about the Lumina 300 is that its incredibly lofty; its baffles appear almost to be bursting, such is the puffiness of their contents. The baffles themselves are arranged in a vertical chevron pattern on the torso, at front and rear, with smaller panels at the sides, to allow movement, and shoulders. The baffle construction throughout is stitch-through rather than boxwall, which saves weight but is of course less draftproof, as cool air can enter at the seams.Luminas hood has a rear volume adjustor and is elasticated around the faceGiven its very low weight, its not surprising that the Lumina 300s features are fairly minimal. The cuffs are elasticated rather than having Velcro tabs, and the hood has a combination of an elasticated hem around the face and a volume adjustor at the back. A single pull-tab is located at the hem for keeping drafts out. You get two zipped handwarmer pockets, and these are roomy enough to accommodate a winter glove in each, and the main zipper is two-way, which is always handy whether for belaying or taking a comfort break. La Sportiva have made sensible compromises to save weight, but if you want more bells and whistles then clearly you need to look elsewhere.You wont be missed on the mountain with the Luminas vibrant colourwaysIn UseAs well as being light, the Lumina 300 is superbly packable; when packed inside its supplied stuffsack its only about 22cm (l) by 15cm (d) (see photo below compared to a 1L Nalgene bottle) which means you dont have to think twice before lobbing it in your pack. The fit is fairly snug but can accommodate at least one midlayer underneath. With the hem coming down over the hips, and the hood covering the lower part of your face, inside the Lumina in the cold is a pleasant place to be. The outer fabric is treated with a PFC-free DWR coating, so does offer some shower protection, however its important to note that the down itself is not treated with a water repellent coating so it wont stand up to heavy/persistent rain. In strong winds the stitch-through baffles are likely to let some cold air in, however the Pertex Quantum the outer shell uses is windproof itself. Speaking of the outer, as durable as it is, if you do get a cut or hole in it you can repair it using the included repair kit a nice touch.Packed-down Lumina 300 besides a 1L Nalgene bottleSo who is the Lumina 300 aimed at? Well clearly it will excel in cold and dry alpine conditions, so whether youre an elite alpinist keeping grams to the minimum, or a trekker, mountaineer or skier looking for a warm, light layer to keep in your pack, the Lumina is just the job. While its not ideally suited to typically damp British weather, its perfectly usable on cold/dry days and should also appeal to lightweight backpackers who want a warm layer for evenings around the camp, or to sling on during rest stops. If you want to step down from the 300 in terms of warmth, La Sportiva also offer the Lumina 100 and Lumina 200 the clue to the jackets performance is in their names, if you hadnt already guessed, with their overall weights coming in at 170g (Lumina 100), 250g (Lumina 200) and 350g (Lumina 300).Overall VerdictThe Lumina 300 seems like a bit of a steal for us at its 325 asking price. The warmth/weight performance is really outstanding, and such a packable and lightweight layer could prove to be one of the most useful pieces in your wardrobe. The Lumina 300 is suitable for a wide-range of uses/situations, however if you want less warmth (and weight) then check out the Lumina 100 or Lumina 200 models.More info: www.lasportiva.comSpecsMain fabric: PERTEX QUANTUM with Diamond Fuse technology, 53% Recycled Polyamide, 47% PolyamideOther fabrics: Lining: 100% Recycled Polyamide Filling: 100% Pure White Down (172 g)Fit: RegularFill Power: 1000FeaturesRepair kit to patch tears and rips2-way front zipCompression bag for packability2 zippered front pockets, compatible with a harnessAdjustable hem for a precise fitElasticated inner cuffs for extra warmthAdjustable, padded hood for greater cold-weather protectionDWR PFC free fabric finishing for light water repellency1,000 cuin Italian down for incomparible warmth and loftPertex Quantum fabric with Diamond Fuse technology for top-level abrasion resistanceSustainabilityResponsible Down StandardRecycled fabricPFC freeJoe Brown/The Climbers ShopOutside