My Signature C Source


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CLAIM TO FAME: A best-selling serum that contains 40 times more Vitamin C than orange, 120 times more than strawberries, and 200 times more than mandarins

FAST FACTS: Packed with potent amounts of vitamins for beautiful, healthy skin; contains 6,000mg of 100% pure Vitamin C; helps prevent premature skin-aging; protects, softens and moisturizes skin; has 20% L-Ascorbic acid concentrate for gentle peeling and exfoliation

PERFECT FOR: Clearing out imperfections and dark spots

Note: Given the nature of Vitamin C, the serum may crystallize around the opening of the bottle. This does not alter the quality of the product.

Feb 29, 2016
”19, M, Oily Skin. This product is incredible. I have a lot of post acne scarring, general redness, and uneven skin; introducing C20 into my routine changed my face in a matter of weeks. I cant even really tell what it did- what I know is that my skin’s redness is much more subtle and that many of my imperfections have been smoothed. I put this on after cleansing and toning, and while I don’t know any of the science behind it, I feel like I can say that it helps all the next products i use become more effective. Make sure you wait 20 minutes after using it for best results.”
– Raynor14 (from amazon.com)

A cost-effective way to change your skin
Nov 4, 2015
”I started using this serum about a month ago and I have already seen big changes in my skin. I am in my mid-30s and suffer from Melasma and fine lines. After a month of use my skin texture is so much smoother and the Melasma that is above my upper lip has faded a lot.”
– MT (from amazon.com)
Holy Grail
Sept 8, 2015
”I have combination/oily skin. After about using thus product for a month, I saw that my acne has improved, my pores were reduced a little in size, and my skin complexion became more even. I would buy this again and I definitely recommend this product!”
– Marla Baconawa (from amazon.com)

WHAT YOU GET: (1) bottle My Signature C Source
Water, Ascorbic Acid, Alcohol, Sodium Lactate, Butylene Glycol, Glucose, PEG-60 Hydrogenated Castor Oil, 1,2-Hexanediol, Phenoxyethanol, Sodium Hyaluronate, Bis-PEG-18 Methyl Ether Dimethyl Silane, Xanthan Gum, Diethoxyethyl Succinate, Ammonium Acryloyldimethyltaurate/VP Copolymer, Carthamus Tinctorius (Safflower) Flower Extract, Citrus Aurantium Dulcis (Orange) Peel Oil, Glycerin, Zinc PCA, Panthenol, Niacinamide, t-Butyl Alcohol, Camellia Sinensis Leaf Extract, Beta-Glucan, Tocopheryl Acetate, Lecithin, Caprylic/Capric Triglyceride, Ubiquinone, Diisopropyl Adipate

STEP 1: Apply after cleansing and toning. Use 2~3 drops and smooth in gently all over face (especially over the aged areas such as pigmented or wrinkled lesions).
STEP 2: Initially, a slight tingling sensation may be experienced (a passing phenomenon).
STEP 3: Mix with several drops of toner to make your skin refreshed without feeling gooey.
STEP 4: After applying vitamin source C20, apply moisturizer to increase efficacy.

If you desire more hydration, use this product with the C20 Vitamin Sleep 9 to 5 Crema Sleeping Cream. After applying the C20 Vitamin serum, apply the sleeping cream over this layer. This combination will amplify the effects of Vitamin C.

Caution: When you use this product, please avoid using any products that contain high levels of AHA, BHA (include Betain Salicylate), Retinal, Vitamin C (Ascorbic Acid). Because of the hot weather, some vitamin serum can be leaked. But this is a natural phenomenon that can only happen to pure vitamins. When this happens, wipe leaked liquid, and keep it in fridge. Then you may use it without any problems.


Formerly known as C20, Tiam has one simple mission: “Helping you to be more beautiful.” Tiam believes that as long as you wish to be beautiful, you will be beautiful! This South Korean brand explores, all over the world, to find the best beauty products and introduce them to inspiring beauty explorers.

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Sit tight, beautiful things
are worth the wait!

176 reviews

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4.1 out of 5
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1 star
Certified Buyer
  • Skin Type Oily
  • Facial Features Mestiza
  • Age 21

Not at all problematic

I was going to give vitamin C a go and because this one was not gonna put a hole on my pocket, out of the array of products from the booming vitamin C industry. I gave it a try, and I did not expect this specific product to work this good! No other skin care product was this effective and gave me immediate results. Giving it a 5 star because not only was it an effective product but it was also worth every penny. The only real downside is the stickyness, which does not really come as a big problem due to it laying low after a while or it going away once you apply a moisturizer. but besides that I don’t think the oxidation is really a problem because that is the nature of Vitamin C. (PLEASE EXPECT PURGING. Do not worry if you see more acne or bumps in your skin after using this, it just means it is working. As long as the blemishes that show up are on your usual areas and is not hurting, do not worry and push through it. Your skin is going to be even better that when you started.)

about 1 month ago
  • Skin Type Oily
  • Skin Tone Fair
  • Facial Features Chinita
  • Age 23

Stings and Easily Spoils

I bought this after using the Dear Klairs as i haven't seen any significant improvement with the product. Since this has a higher percentage of vitamin c i thought i might see better effects. However, this product stings and has a sticky feeling when applied which i hate. I used this during the night time and be careful as this will stain your pillows. After finishing the bottle, i have not seen drastic difference. My scars faded a bit but i have used different products that helped me achieve same results without the sting.

about 1 month ago
Certified Buyer
  • Skin Type Oily
  • Skin Tone Fair
  • Facial Features Chinita
  • Age 20

Pretty good!

This was my first vitamin C serum ever and TBH I think I kind off oxidized mine on purpose. When it came in the mail and I opened it, it overflowed as if it was champagne. I don’t know why that happened but I panicked and closed t again bc i didn’t want to lose any product. I waited for it to calm down and when I opened it again it, the substance was already yellowish. I heard the more clear the vit c serum is the more effective it’ll be. Anyway, even thought it did went a bit brassy it still worked. Maybe if it didn’t oxidize it wouldn’t made my skin glow better.

about 1 month ago
Certified Buyer
  • Skin Type Combination
  • Skin Tone Fair
  • Facial Features Mestiza
  • Age 24

Its okay

I was desperate to buy Vitamin C because I read that it’d help fade my acne marks. When I saw this I immediately purchased it because its more affordable compared to other brands. It didn’t caused breakouts but sadly it didn’t help fade my acne marks as well. I kept it inside my cabinet so it wont oxidized right away but the dark packaging helped preserve the product too.

2 months ago
Certified Buyer
  • Skin Type Oily
  • Skin Tone Fair
  • Age 23

Better than expected!

I used to apply the vitamin c from The Ordinary for my nighttime routine but I saw this vitamin c from TIAM on a much discounted price (& since the one I used before was about to run out) I bought 2 of these in a heartbeat. Been using this for a week now and it's better than what I expect. It doesn't leave brown stains on my clothes and pillow cases unlike the vitamin c from The Ordinary. This one from TIAM only dries and leaves flakes on my face in the morning (no stains! less worries! haha) The brightening is the same. But on my current product I'm more cautious on handling it since many reviews said that it oxidizes easily, unlike the one from Deciem where I can store it in room temperature. But all in all, I'm happy and contented with TIAM. Got 2 bottles in a price of 1, and it's much fun applying a face product with a dropper. 😅😄

6 months ago
Certified Buyer
  • Skin Type Sensitive
  • Skin Tone Medium
  • Facial Features Chinita
  • Age 21

Does its job

When I had a trip to the beach and got my skin badly burnt, I used this along with Farmstay grapeseed serum. Did its job in skin repair and brightening. However it oxidized rapidly even when stored in a ref. Also had a stinging sensation every time I apply it. So I did not finish the bottle at all. Worth the try.

6 months ago
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