Try Wah Chan, Lazo, Lavin New York and see first.

I am assuming you are looking for engagement ring. Unfortunately, in reality, if you want a diamond with a proper grading report, RM 1K inclusive of both diamond and ring is basically impossible.

However, you can opt for other gemstones, like aquamarine (something I like personally). The cost can be lower. The other cost that you may want to factor in is the cost of the ring setting itself. You can see that Lazo has a range of different Karat ring settings, from 9K to 18K. Basically 9K means out of the whole ring, 37.5% is real gold, while others are other materials that make you the alloy that is used to make the ring. Therefore, higher Karat means more gold, which in turn means more expensive.

Assuming you opt for 9K ring setting + gemstone, the cost will most likely still be over RM 1000.

You can find gemstones from La Fiancee or ZCOVA:
https://www.facebook.com/LaFianceeGems/
https://www.facebook.com/zcovajewels

I am not sure whether they willing to work with 9K gold or not though.

To make it even cheaper, you can simply opt for sterling silver ring. Silver setting is cheap but if you are getting a customized one, majority of the cost will be on the labour an design, not the material, as it is a custom piece.

Another option is to opt for lab-grown diamonds. They are basically diamonds, just not mined from earth, and naked eye can't distinguish the difference. A lot of them do come with lab reports as well. More and more companies are pushing the sales for lab-grown diamonds due to its affordability. Love & Co is one of them. I am not sure what lab report (certificate) Love & Co use, but if you need a nice sounding brand behind your purchase, then perhaps you can consider them.

The other company that I came across recently was GrandQuover. They have access to lab-grown diamonds graded by IGI. They brand their diamonds ACE DIAMOND. They are currently running a promotion for their lab-grown diamonds: https://www.grandqouver.com/ace-diamond

They also offer sterling silver engagement ring that comes with moissanite: https://www.grandqouver.com/silver-sterling-moissanite. Prices are attractive.

Lavin New York - https://www.lavinnewyork.com/pages/Engagement is also another company that sell affordable GIA graded stones and also affordable ring settings. Although 1K still very much impossible, you can ask them and see what and how they can assist you.

About Lazo - while Lazo received some negative feedback, I believe they do have their fair share of positive reviews. I would recommend you to pay a visit to several different jewelers and make a comparison. Take everything with a pinch of salt and make your own judgement. What I can say is that after looking at their prices, affordability is certainly one of their selling points. Personally if cost is my main concern, I will probably just stuck with my budget and get this: https://lazodiamond.com.my/product/9k-white...nd-ring-drf110/ for 2 main reasons: It is within my budget and I can get after-sales service.