Transparency and your rights · 14 Oct 2026 · 2 min read

Three price components: how Kim Bảo Minh Châu prices a piece

A diamond ring's price is metal value, labour and stone. Shown separately, they let you compare, negotiate the right line and know in advance what you would get back.

Written by Kim Bảo Minh Châu

Close-up of the Lotus ring, ten lotus petals around the centre diamond

Many jewellery tags show a single number. You cannot tell how much is gold, how much is craftsmanship and how much is the stone. When you sell the piece back, the figure is far lower and nobody explains why. Kim Bảo Minh Châu (KBMC) splits the price into three lines so you can check each part.

Three lines on the tag and invoice

Component	What it is	When it changes
Metal value	Pure gold in the piece times the day's gold price	With the board, several times a day
Labour	Design, casting, setting, polishing	Fixed per design
Stone value	Price per stone, matched to its report	With the stone list, rarely

How metal value is calculated

An 18K ring weighing 3.20 g does not contain 3.20 g of pure gold. 18K is 750 parts per thousand, so the pure gold is 3.20 × 0.750 = 2.400 g, or 0.640 chỉ. KBMC calls this the fine-gold weight and multiplies it by the 9999 selling price on the board in force.

The 24K Golden Grain ring, whose fine-gold weight is almost its full weight

For 24K gold, purity is 999.9, so fine-gold weight almost equals weight. That is why plain 24K rings sit close to the gold price, while labour is a larger share of 18K jewellery.

Why three lines help you

You can compare. Put two quotes for the same design side by side and check each line: does the gold match the published board, how far apart is labour.
You negotiate the right line. KBMC promotions apply to labour only. Everyone buying at the same moment pays the same gold price.
You know the buy-back figure. On buy-back, labour is not refunded; metal and stone follow a published formula. The invoice lets you estimate your figure straight away.

A full example

18K ring, 3.20 g of metal, one diamond listed at 20 million VND, labour 2.5 million VND. Assume a 9999 selling price of 14.38 million VND per chỉ:

Metal value: 0.640 × 14,380,000 = 9,203,200 VND
Labour: 2,500,000 VND
Stone: 20,000,000 VND
Total, rounded up to the nearest 1,000 VND: 31,704,000 VND

Figures illustrate the method only.

Where to check

The KBMC gold board is published on Gold prices, timestamped to the second. The full formula is on How we price. Every invoice stores the board it used, so any past transaction can be traced to its exact price.